Tap Aerators

What are tap aerators?

Aerators are designed to reduce the flow of water on your water taps in the kitchen and bathroom, reducing your overall water usage. The savings will be bigger if you are on metered water, however even if not, the aerators will mean that you use less hot water – so you will save on both water bills and your heating bills (normally gas from central heating).

Saving water is ethical because it’s good for the environment. More and more fresh water is being used in homes, businesses and production processes, which means there is less of this valuable commodity. Sewage treatments are expensive because they are very energy intensive, which means if we could do something to save water upfront it would lower the CO2 emissions as well. Water can be saved throughout the home or work by changing habits and installing water saving devices such as tap aerators.

How do tap aerators work?

Taps can flow at 18 litres of water per minute and costs approximately £0.03 for every minute the taps are running. Hot water is even more expensive as you use energy to heat it. the biggest savings are realised on bathroom sink and kitchen taps, as here water tends to be turned on and off frequently and throughout the day.

The tap aerators sit at the bottom of the tap reducing the flow of water that comes out by mixing water with air while maintaining the existing pressure that you are normally used to. The aerators basically act like a sieve, separating a single flow of water into smaller streams and also reduce the space in which the water has to flow into.

A tap aerator can reduce the flow of water by up to 10 litres per minute, so this will obviously help you use a lot less water.

Some tap aerators on the market can reduce the flow to operate at 6 litres per minute, therefore further reducing your consumption.

How do I install a tap aerator?

Tap aerators are easy to install. If your existing tap has an aerator you will need to unscrew it and replace it with the new more efficient water saving one. Turn the existing tap aerator anti-clockwise until you unscrew it from the tap. If the existing aerator doesn’t move when you try and move it you may need adjustable pliers to remove it. Then you simply screw in the new aerator (turning it clockwise) until the fitting is secure.

Male vs. female aerator fittings

The type of aerator replacement you buy will depend on the existing tap fitting. A male fitting has the thread on the outside, whereas the female fitting has the thread on the inside. Please check which fitting you have before going out to purchase a replacement.


    Water Saving Shower Heads

Water-saving shower heads

The average shower in the UK last 8 minutes and in that time an estimated 60 litres of water is used. Even if you don’t pay for the specific amount of water you use (i.e. you are unmetered), you still need to heat the water for showers, so using less hot water, means you have to heat less, so you save on your heating bills.

Elsewhere in our water saving section we look at behavioural changes you can make to use less water when you are in the shower, but a water saving showerhead is a solution that you can install in your shower to dramatically reduce the amount of water you use.

How do water-saving shower heads work?

These shower heads work by restricting the volume of water that they allow to flow through them. Newer models can reduce the volume of water used by half, but still provide an enjoyable showering experience!

It is important to point out that if you have an electric shower or a shower with very low pressure, a water-saving shower head will probably not be suitable for your home.

There are two main types of ‘low flow’ water saving shower heads.

Non-aerating shower heads

These work by restricting the water flow through them and squeezing it through very small holes. This means the water comes out under more pressure, so it gives a harder, more massaging showering experience.

Aerating shower heads

These are slightly more complex and work by mixing the restricted flow of water with air, therefore the water appears to come out of the showerhead in higher volume, replicating a normal shower, this will therefore provide a softer showering experience.

How are low flow shower heads fitted?

Both types of shower head are fairly easily to install. If you are replacing a shower head on a flexible hose, then you simply need to unscrew the existing shower head and screw on the low flow one in its place.

To ensure a really snug fit and no leakages from the top of the hose, you can use plumbing tape. Simply cut a short length of plumbing tape and wrap it around the thread of the new showerhead and screw this into the hose.

To replace a fixed showerhead, it is exactly the same principle except you might need a spanner to remove the old showerhead and tighten the new low flow one into place.

Aerated versus non-aerated showerheads

Since aerated showerheads combine room temperature air with the water to ‘flesh it out’, people tend to increase the temperature of their showers to compensate.

Water coming out a non-aerated showerhead will come out under higher pressure so the jets will feel harder on the skin. Conversely, the aerated showerhead will produce a far softer showering experience.




    Water-Saving Behavioural Changes

Behavioural changes to help save water

Regardless of the type of tariff you are on, the less water you use, the less you will pay on your bills.

A litre of water delivered to your home works out at about £0.0029 in a metered home, so saving one litre isn’t really going to make too much of a difference, however you will that by implementing some of the behavioural changes we have listed below that the savings quickly add up.

Even if you are unmetered, you still have to pay to heat water (heating water accounts for about 30% of your gas bill), so by implementing these changes you will be using less hot water, therefore saving on your gas bill.

In the bathroom

Taps running unnecessarily – A running tap wastes over 6 litres of water per minute, so if you turn it off while you are doing your teeth (1.5 minutes), you could potentially save 18 litres per day.  If a family of 3 were to all do this, they would save over 6,500 litres per year, which works out at a £15 annual saving.

By the same token, when you have a shave, fill the basin up with warm water first, then you don’t need to keep the tap running while you are shaving.

Leaking taps – this may seem like a no-brainer but a leaking tap could waste about 5,500 litres per year, so getting the spanner out to tighten it back up could save you about £13 a year.

Running deep baths – a nice deep bath is a great way to relax, but filling a bath typically uses around 80 litres of water, so try and replace the daily bath with a shower, so you will then use about a third of the water.

Showering time – This is really simple one, take shorter showers. The average shower in the UK lasts for 8 minutes and in this time you will use about 62 litres of water (a power shower may use as much as 136 litres in this time). If you were to spend just 4 minutes in the shower, it would save 30 litres every time you showered, which for a family of 4 taking daily showers could save 44,000 litres of water per year so a saving of £75 just on the water (the heating savings would be even more significant). You can also combine showering and doing your teeth for example for an even more efficient use of water!

Using your toilet as a bin – We all know the primary function of a toilet and each time you flush it uses about 9 litres of water, therefore using it to dispose of a snotty tissue or facewipe is a big waste.

Check for leaky cistern – It is also worth putting some food colouring in the cistern of your toilet and seeing whether this flows down into the bowl without flushing, since this will show there is a leak in your cistern mechanism, which you should try to address.

In the kitchen

Leaking taps – as we said before, a leaking tap could waste about 5,500 litres per year, so getting the spanner out to tighten it back up could save you about £13 a year.

Filling washing machine/dishwasher – Washing machines and dishwashers have made life very easy, however they are quite water intensive pieces of kit. A washing machine will use anywhere between 33 and 72 litres per wash on typical settings, while a dishwasher will use anywhere between 10 and 21 litres. Nowadays both of these appliances will have eco settings built into them, which will reduce the amount of energy and water they use to operate, so ensure you are using these settings when possible. In addition only use them when they are full; ensuring a full load is the most efficient way to run both dishwashers and washing machines.

If you don’t have a dishwasher, it is much easier to fill the sink with water and let things soak before attacking them with a scrubbing brush under a running tap. As mentioned above a running tap uses about 6 litres of water per minute, so fill up the sink and let nature work its magic!

Running through cold water – Everyone prefers cold water to drink – Fill a jug with tap water and leave it in the fridge, then you don’t have to run the tap for ages just to get a cold drink.

    Water Bills in the UK

Water bills in the UK

In the UK, the majority of households get their fresh water from the mains and they are charged in one of two ways:

Regardless of whether the household is metered or not, in the water bill there is also a charge for water to be removed from the property (mostly greywater, for example when water runs down the sink) and surface water drainage, which is the cost associated with draining rainwater away from your property.

On the whole, properties built prior to 1990 are unmetered and therefore pay the unmeasured charge, while properties built after this date tend to have meters and therefore pay the measured rate.

The unmeasured charges are based upon the 1989/90 rateable value of the property. The rateable value of properties varies dramatically, and is based on the notional rental value of the property taking into account factors including the location, size and type of the property.

Should I get a water meter? The rule of thumb

From a money-saving perspective, both the measured and unmeasured tariffs can be beneficial depending on the particular situation of the household. Unfortunately if you are metered you cannot go back to the unmeasured tariff. However you can move from an unmeasured tariff to a measured tariff, by requesting your water supplier installs a water meter at your property.

In this example scenario, we will highlight the situation in which this might be a good idea.

Your home is a 1970s property, and the property next door is a similar age and size. There are 5 people living next door, while in your home there is just you. Since it is highly likely you will be paying the same 1989/90 rateable values and you will both be charged the same amount per year on your bill – although their usage is likely to be 4x higher than yours.

In this situation it would make sense to have a water meter installed in the property. The general rule of thumb to help make this decision easier is as follows:

If you have more bedrooms in the property in your property than people living there, then you should consider installing a water meter.

For a more accurate assessment of your property, the Consumer Council for Water has developed a handy little tool to help you decide whether it is cheaper to go for a meter if you are currently being charged based on the rateable value (i.e. you are unmeasured) which can be found here.

So you might think that if you are using water based on the rateable value, it is really irrelevant on how much water you use, because your bill will remain the same. Unfortunately this isn’t the case!

Linking water to energy bills

What’s the relationship between energy bills and using water?

Well it’s likely that much of the water you use in your property will be heated, in fact it is estimated that 25% of the average UK family’s energy bill is spent on heating hot water.

Therefore regardless of whether you are have a water meter fitted or you live in an unmetered property, being a little bit more careful with the way you use water could translate into significant money savings on your energy bills!

There is the added benefit that using less water helps to save the planet, since 5% of the UK’s greenhouse gas emissions are caused by residential homes heating water, therefore the less water that gets heated, the less CO2 that is released into the environment.

Our two top tips:

1.     Determine whether you would be better off having a water meter or not based on your living arrangements.

2.     Use less water, even if your bills are fixed. The less water you use, the less you need to heat.

    Water as a Finite Resource

Fresh water is a precious resource

Water is incredibly abundant, covering about 70% of the Earth’s surface; however the amount of fresh water available to us is actually considerably less. 97.5% of the water on earth is actually salt water, leaving only 2.5% as freshwater. 70% of this fresh water is actually frozen in the icecaps of Antarctica and Greenland.

This leaves less than 1% of the water on earth easily accessible for animals to use, and although this is continuously replenished via the water cycle, the world’s ever-growing population is putting more and more strain on the fresh water supply.

In the UK, the average person uses about 150 litres of water a day. That’s about a tonne a week. This takes into account cooking, cleaning, washing and flushing. This is water that has been cleaned, treated and pumped from reservoirs, rivers and aquifers, and too much of it still leaks out of pipes before it ever gets into the home.

We’ve come to expect some of the highest quality water in the world, and an almost endless supply, for brushing our teeth, drinking, taking a shower in the morning or preparing food. But we also use this water to heat our homes and offices, clean our clothes, water our gardens, wash our cars and in thousands of industrial processes. Non-renewable energy production uses vast amounts of water. The more we use, the less we leave for the countryside and the wildlife around us.

The issue we face

The problem we face is this: because of our need to adapt to climate change and population growth, our water-intensive lifestyle and other pressures such as changing land use, we need to find ways of using water much more efficiently if we are to continue to enjoy high standards and constant supply.

By 2020 the demand for water could have increased by 800 million extra litres of water a day. This figure for required additional water doesn’t even taken into account embedded water, which would increase this figure many times over.

The freak flooding we have faced in the UK in recent years is the other side of the climate change coin. UK environmental leaders have warned that the risk of flooding and water shortage in 2013 has increased because the Government has been ‘too slow’ in taking action to improve water management. 16 leading environmental organisations have specified that a long-term, sustainable approach is needed which ‘works with our natural water systems’ to avoid increasing water problems.

The Blueprint for Water group says that after two dry winters, it took Britain’s wettest ever summer to narrowly avert a serious drought. They warn that despite summer 2015’s flooding, another series of dry winters would put Britain right back under serious risk of drought.

    Rainwater Harvesting

 Introduction to rainwater harvesting

Rainwater harvesting (sometimes referred to as RWH) describes the process of collecting rain that falls onto a catchment area. In most cases, the catchment area is the roof of your house, where the rain falls and is then bought to a central point via guttering and down-pipes, before entering a storage tank. In more straight forward water harvesting systems, this storage tank can simply be a water butt, where the water can be tapped off and used in the garden. There are more complex water harvesting systems that are discussed later, which filter the water, even potentially getting to a suitable level for drinking. However on the whole, water harvesting is much simpler than recycling grey water or treating domestic sewage.

Uses for harvested rainwater

If your major catchment area is your roof, then we recommend putting in a very simple water butt at the bottom of a drain pipe so it catches rainwater that can be used in times of drought, to water your plants. When the rain falls on the roof though, it will likely pick up pollutants, potentially from the air (e.g. exhaust fumes), but also things like bird faeces on your roof, therefore water from this source is not drinkable unless it undergoes further treatment.

Using a simple sand filter system, you can remove the vast majority of pollutants and larger contaminants, so this water will then be okay to use to flush toilets. In order to do this you will need to use a specialised sealed water container and a submersible pump to get the water to where you need it. This will increase the cost of your water harvesting system.

If suitable treatment is in place you can make the rainwater suitable for drinking too. Filters can be used, e.g. a particulate filter that remove particles that are larger than 5 microns in diameter, which can be used in conjunction with ultraviolet light sterilisers, which also kill any dangerous microorganisms in the water to make the water drinkable. Due to the filtration technology needed to support this system, this will be the most maintenance heavy and financially expensive system, but it will certainly reduce your reliance on the water companies once installed and over time will naturally lower your water bills (after the initial capital expenditure).

It is also important to note that there are other catchment areas to fulfil your rainwater harvesting needs, such as roads or parks. These have the advantage of a massive catchment area, so work better when there is little rainfall, but at the same time the water runoff from these catchment areas is more contaminated with things like oil from cars and other waste, so it takes more filtration to get the water into a suitable fashion for use in your home.

Types of rainwater harvesting system

A simple water butt can be bought from most good DIY stores (e.g. Homebase or B&Q), and they start from about £30-£40. They obviously come in different shapes and sizes to accommodate your needs, but obviously if you have very little rainfall, then getting an enormous water butt may be unwise, as it will be more expensive and take up more room when it is not actually going to be used. In addition, if you let it fill over the winter, you can use it in the spring to provide water for your garden; but note that if the water has been stagnant for quite some time, it is highly probable that algae and other microbes may have made into their home!

If you are looking for a slightly grander water harvesting system, with water to be used inside the house (not just for gardening and washing the car), but for completing everyday tasks such as flushing the toilet, it is worth sizing the storage tank by looking at several factors.

Obviously the local average rainfall is the major factor, the more rain that falls the more rainwater you can collect. The size of the roof will obviously play a large part in this, as this essentially defines your catchment area. It doesn’t matter if you live in the vicinity of Victoria Falls, if you only have a small roof, it is going to limit the amount of water you can collect.

The final thing to think about is the actual volume of water you require, ideally you don’t want the water to sit in the tank for extended periods of time as algae and other microbes will start growing. Ideally you almost want to use the water as you harvest it, minimising turnaround. A tank size calculator can be found here, though you will need to know the approximate dimension of your house to use this tool.

Water harvesting building regulations

These systems are best installed as a new build project or when undergoing major regenerations to a house. In the UK all new were rated under the Code for Sustainable Homes (CLG 2008), but this was replaced by a voluntary quality management scheme in 2015, which is the Home Quality Mark (HQM). Although not mandatory, there are standards in the HQM, which talk about the best practices to reduce potable water consumption – including harvesting rainwater as one of the ways to meet this. The theory being that to decrease the consumption of potable water, alternative sources of water are used for lower grade uses such as toilet flushing and irrigation. Most of these systems don’t need planning permission, and as of 2007 councils were directed to give sympathetic handling of planning permission to applications that include rainwater harvesting.




    Greywater Recycling

What is greywater?

Water used in homes has long been thought of in terms of clean drinking water (known as potable water) coming into the house from the mains and sewage going out. However, the wastewater from baths, showers, washing machines, dishwashers and sinks fits somewhere in-between and this is referred to as greywater, which typically makes up between 50-80% of a household’s waste water.

Roughly a third of the water used in households is used in toilets, which comes into contact with human waste and is known as blackwater. Greywater is much easier to treat and recycle when compared with blackwater because there is no faecal matter that is a haven for harmful bacteria and disease causing pathogens.

If recycled properly, greywater can save approximately 70 litres of potable water per person per day in domestic households, therefore greywater recycling is one of a number of water solutions that we should look to in order to decrease our usage.

If your house is metered, recycling greywater can significantly reduce the volume of water you use thereby saving you money on your water bills.

How does greywater recycling work?

Please remember that greywater is never going to be safe to drink, even when treated. However the reclaimed greywater can be used to flushing toilets, wash clothes and water your garden.

There are various ways to treat greywater, ranging from very simple methods to complex fully automated treatment systems, depending on what you want to use the water for.

Each of these is described in detail below.

1. Direct use systems (for watering plants)

If you don’t want to treat the water, you need to use it very quickly since bacteria present in the water feed on any organic matter present (e.g. skin particles, hair and detergents) and multiply very quickly. Once the bacteria have used up all the oxygen it will become foul smelling, and these anaerobic bacteria can contain harmful human pathogens.

Using this greywater is relatively simple, you can either syphon it directly from the bath or sink or you can fit a valve to the external waste pipe allowing you to direct the water to a water butt, so it can be used as needed to water the flowerbed.

It is not recommended to use greywater on fruit or crops, since there is a chance the plant will ingest the harmful pathogens when they are watered.

2. Biological Systems (non-food debris)

Sand filter method

The initial filtration can be simply achieved using a sand filter that removes any large particles. The greywater enters the top of the sand filter and travels down through the sand via gravity, with the sand removing any sizeable particles.

Once the greywater has been pre-treated, it can be filtered using a very simple soilbox consisting of four layers of material. The top layer is roughly 2 feet deep of humus-rich top soil, which sits on a bed of very fine building sand, which in turn sits on a layer of course sand. Finally there is a layer of pea-shingle at the bottom to achieve excellent drainage. The water is initially pumped in at the top of the soilbox, where it travels down via gravity through the 4 levels. Most of the filtration takes place in the topsoil level where soil organisms feed and reproduce using the nutrients in the soil, essentially purifying it.


Another way of treating the greywater is using a wetland, where the water is retained at a level close to the surface, allowing aquatic plants such as reeds and bulrushes to flourish. Subsurface wetlands are considered better for treating greywater, as it lowers the chance of odours escaping, there is less chance of freezing during cold weather and has lower human contact, which is potentially dangerous. Bacteria, both aerobic and anaerobic treat the greywater. In addition, the roots of the plants absorb dissolved organic materials, helping speed up the process.

3.Biological systems (including food debris)

Greywater with food debris in it needs to be treated anaerobically using a septic tank (see treating domestic sewage for details on how a septic tank works). The water that comes out of the other end of the septic tank can then be treated with the soilbox filter or using wetlands as mentioned above.

4. Mechanical filters (for using the water to flush toilets)

It is a relatively simple process to undo the U-bend under a sink and capture wastewater in a bucket, which you could then manually pour into the cistern of a toilet. However practically, this is quite a time consuming job for something that can be easily automated.

Ecoplay is one of a number of companies that has produced a greywater pump that pumps water away from a variety of greywater sources including washing machines, showers and utility sinks. When the water enters the pump unit, it can then pump the water vertically to where it is required. The water is then treated in a storage tank (normally chemically by adding chlorine) before it is sent to the cistern of a toilet or the washing machine.

The greywater can also be treated using more expensive mechanical filters, such as microfiltration systems using membranes. We have looked at this in more detail in harvesting rainwater – so please look there for more information.

Uses for treated greywater

Using greywater for flushing toilets

Typically, about a third of household water is used for flushing the toilet, but reclaimed greywater can be used to fulfil this purpose saving valuable potable mains water.

Once the greywater was gone through the complete filter process and treated with chemicals to kill all microorganisms it can be pumped from source back to the toilet via a header tank, and used as appropriate.

Using greywater for watering plants

A great deal of water is also used in the summer to water plants – this is again a waste of potable water. This can be a major issue where we have droughts, which was experienced quite recently, back in early 2012.

The greywater can be used in combination with an irrigation system to water the garden automatically. This is good to have in place because it targets specific areas of your garden so it is a more environmentally friendly way to care for it.

Home water irrigation systems vary in complexity, with companies offering whole systems to maximise efficiency by very specific targeting.
This water does not need to be treated with chemicals as any organic material remaining in the water can be absorbed by the plants. It is not recommended to use this type of water with home grown vegetables.

Using greywater to wash clothes

Reclaimed greywater can also be used for washing clothes; again this has to be treated to a similar level as the water used for toilets. And like the toilet greywater, plumbing needs to be put in place to redirect the water to the appropriate place in the house.




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      Water Saving Toilets

    What are water saving toilets?

    In the 1830s the average person in the UK would have got by on just 18 litres of water per day, however nowadays we are using over 135 litres a day (7.5 times the volume).

    Toilet flushing accounts for 1/3 of water used in the home today; one toilet flush using an older style toilet uses 14 litres of water. So what can we do to lower our water bills and use less water?

    Well, new dual flush models use as little as 2.6 and 4 litres per flush, so only 20% compared with older toilets, while composting toilets use no water at all.

    Dual flush toilets

    A dual flush toilet is a high efficiency toilet (HET) that conserves water by offering a choice of two different toilet flush volumes – a low volume flush for liquids and a full volume flush for solids. These water saving toilets have a much larger trapway (the hole at the bottom of the bowl) than traditional toilets and use a wash down flushing design (as opposed to a siphon system), so they can use much less water to get the job done. Since they have the larger trapway, there is much less clogging associated with this type of toilet. The main issue with them is that since they use less water, flushing doesn’t always get rid of all the waste so you will be more active with your toilet brush.

    Replacing an old standard toilet with a new dual flush commode will ensure you use less water when you flush the toilet, however if you do not want to go as far as replacing the toilet, you can retrofit the dual flush functionality onto an older style toilet. The bowl will still use the siphon system to get rid of the wate, but you will get to choose whether you use the partial or full flush.

    Pressure assisted toilets

    Pressure assisted toilets are used more in commercial premises that in the residential setting since they are more expensive to buy and install and they are louder when flushed. They are however growing in popularity since they are a water saving toilet and they leave the bowl cleaner because the flush is stronger and the water level in the bowl is higher. Despite looking identical to traditional toilets, they operate using compressed air which removes more waste products when you flush. The air is compressed as water enters the toilet cistern as normal, so no additional pumps or other devices are needed.

    Alternative quick win on existing toilets in your house

    Install a cistern displacement device in your toilet – these can be obtained free of charge from your water company (or you can simply fill a plastic bottle with water and submerge it within your cistern). They work by displacing water in your cistern so that the volume of water in your flush is reduced by between 1 – 3 litres. Please note, that you do not need a cistern displacement device if you have a dual flush toilet, also if you are going to install a displacement device be sure it does not get in the way of any of the moving parts in the cistern, as this might cause issues.

    Composting toilets

    The most water-efficient type of toilet is the composting toilet, which typically is a completely dry toilet, relying on aerobic processing to treat the waste. In this type of toilet, the solid waste is composted by microbes, while the urine is diverted off (as too much moisture in the process can lead to anaerobic decomposition which results in nasty odours). The solid waste is often mixed with a bulking agent such as sawdust to increase the surface area for the microbes to do their work. These tend to be found in places that have no suitable water supply but may be suitable if you have a large garden in your property.

    The importance of saving water

    Saving water is important in the UK despite the fact that it appears to rain a lot throughout the summer and winter months. Recent wet summers and even mild, wet winters have kept the gardens nice and green and our rivers flowing. Despite having a seemingly wet climate some parts of the UK are experiencing water shortages, for instance in April 2012, much of the country was subject to a hosepipe ban, due to very little rain in the preceding 18 months (it was actually noted that this was the driest spell in the UK for more than 100 years).




      Domestic Sewage Treatment


    Recycling domestic sewage

    Water is becoming an absolutely key resource in the UK, especially in the south and the east of the country. With supply limited as a result of increased frequency of droughts, and ever increasing volumes of water demanded, recycling water is imperative to ensure supply can still meet demand. Recycling domestic sewage is one way of recycling water, and this also has the added benefit of cutting the cost of industrial sewage treatment processes. Domestic sewage treatment is a relatively simple process and is described in detail below, however first it is important to make the distinction between greywater and blackwater.

    Greywater is the wastewater that comes from showers, washing machines, and sinks. It may have particles and contaminants but they are not dangerous.

    Blackwater is sewage wastewater from toilets or dishwashers and can contain food particles, faeces, and other human bodily fluids which are considered hazardous both to the individual and, if released into the ground, soil.

    Currently it is normal for greywater to get recycled while blackwater gets disposed of and is treated by properly installed sewage treatment works.

    Current practices are based, understandably, on assumptions of hygiene issues. Indeed, treatment of blackwater is more complex than the treatment of greywater, but despite the added complexity there is still a strong argument to recycle this type of sewage wastewater; with the following sections summarising the processes and costs and benefits of doing so. 

    How the blackwater recycling process works

    Blackwater is generally not treated domestically, but instead the process is completed by centrally installed sewage treatment works. However, there are reliable systems now that act as hygienic domestic sewage treatment works, filtering the blackwater sufficiently so that it can be used outdoors in watering lawns and plants.

    Top of the range systems are available that can even filter blackwater to purity levels that make it fine for human consumption. However these systems come at a very high cost with high associated maintenance costs. There is also a certain stigma attached to this, with people uneasy about drinking ’cleaned up toilet water’.

    The filtering system for removing usable water from blackwater sits externally to the house. Water is piped to it, and then it goes through a process before being used to water the lawn or non-food gardens via underground pipe systems. As discussed above, unless you have a top of the range domestic sewage treatment works in your back garden, the recycled water from blackwater is not normally suitable for drinking. If you intend to use the water in the garden, it is advisable not to use this water on edible crops because it could still contain harmful bacteria, which poses a danger to the individual.

    The blackwater filtering process

    The following section looks at five steps involved in the filtration process, that takes place as part of your domestic sewage treatment works.

    The primary tank

    This where the sewage wastewater initially runs into as it flows from the home via gravity and pipes. Here, the sewage sits for a period of time, usually 24 hours, while large volume of bacteria works to break down the big particles. After this short period the settled blackwater is pumped to the secondary tank.

    The secondary tank

    When the settled blackwater is pumped away from the primary tank, it goes into the secondary treatment tank. This tank is then further separated into three stages to help with the continuing processes.

    Ventilation stage

    The first chamber in the secondary treatment tank begins the ventilation stage. This is where water and air are injected into the tank at timed intervals so that the tank contents are churned. Bacteria in the tank then settle so they can feed on the sludge in the tank. When this is complete, the water is moved to the sludge settling chamber.

    Sludge settling chamber

    The water that is piped from the ventilation chamber ends up in the sludge settling chamber. A bacteria biomass mechanism forces sludge downwards and the partially treated water upwards to be collected and sent on to the irrigation chamber stage.

    Irrigation chamber

    When the water is piped out of the sludge settling chamber, it is eventually pushed into the irrigation chamber. Here, it is clarified and chlorinated, which is the last step of the process. The water can then be piped out of the system and sprinkled on plants in the garden.

    Final thoughts on treating blackwater

    There is certainly a stigma of drinking treated blackwater, however recycling water is an important aspect of a more sustainable life, even if the water is only to be used in the garden. In April 2012, the UK suffered a hosepipe ban due to lack of rainfall over the prior couple of winters. In fact it was noted that the preceding 18 months were the driest on record for more than a century. Therefore we all need to do our bit and try to use less water, or recycle more of the water we use – so recycling blackwater is a great way to help this cause.

    The fact that many ‘off-grid’ remote places already operate their own domestic sewage treatment works in their back garden shows that this technology is reliable and proven, therefore this technology may be suitable for installation for the home or a community that wants to do its bit to recycle water.




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