Search This Blog

Tuesday, 8 May 2012

Grey water recycling


Greywater is waste water from showers, baths, washbasins, washing machines and kitchen sinks. You can collect it from some or all of these sources and, after treatment, use around the home for purposes that do not require drinking water quality such as toilet flushing or garden watering. However, water from kitchen sinks and washing machines tend to be more contaminated than shower etc and so should not be used as a source of grey water unless you are thinking about a more complex treatment system.

The final use of the recycled water is really important to consider. If you have low flush toilets, no garden, or are the type of family that rarely washes the car, then looking at new grey water recycling systems should be a low priority.

The pie chart below sets out average use for the UK. The only segment that shines out for grey water use is the toilet flushing. Given that water use can be radically reduced (around 50%) by using equipment like Interflush or Mecon variable flushes the figures that you can affect by recycling water are quite minimal.

Currently there are no regulations to cover the quality of reused water. Although there are some national standards relating to reused water that have been developed by the British Standard Institute and these would require a system that has:

• a tank for storing the treated water;
• a pump;
• a distribution system for transporting the treated water to where it is needed; and
• some sort of treatment.

So if you are to store the water then a more complex (and hence expensive) system is required. This is because untreated greywater deteriorates rapidly in storage.This rapid deterioration occurs because greywater is often warm and rich in organic matter such as skin particles, hair, soap and detergents. This warm, nutrient-rich water provides ideal conditions for bacteria to multiply, resulting in odour problems and poor water quality. Greywater may also contain harmful bacteria, which could present a health risk without adequate water treatment or with inappropriate use. The risk of inappropriate use is higher where children have access to the water.

Do not worry, though, as it is possible to reuse greywater without any treatment provided that the water is not stored for long before use. For example, once bath water has cooled, it can be used directly to water the garden. Very simple devices are available to make this practical. Among these is the ‘WaterGreen’ by Droughtbuster UK Ltd , which is essentially a hose pipe with a small hand pump to create a siphon. This allows cooled bath water to be taken directly from the bath and sent through the hose to the garden. Using greywater in this way may not suit everyone, but it does provide an inexpensive and easy way of saving water and avoids greywater storage issues. It is particularly useful for keen gardeners when water use restrictions are in place. Experts usually advise that greywater should not be used on fruit or vegetable crops.

Other equipment is designed to reuse greywater direct from a sealed main drainage system. For example, a valve can be fitted to an external waste pipe that drains water from the bath or shower. This valve can be used to direct greywater to a water butt where, once cooled, it can be used for garden irrigation. An example of this type of valve is the ‘Water Two’ valve, which can be fitted to existing piping and switched to either divert greywater to a drain or to storage.

Our advice therefore would be to think about water use and to reduce consumption as the first course of action. Once this has been minimised, then you can re-assess what your demands are and then see if grey water use is right for you. Note that rain water harvesting and use might be a better option than grey water use.

Wednesday, 2 May 2012

Self build the way forward for communities?

This is a picture of the Wintles development in Shropshire that is based on the principles set out in 'A Pattern Language'. The houses were laid out in a master plan, but people have been involved in designing and building their own homes.
This is a set of new houses that have been built by a major house builder in the UK.

I think that it is clear that we are dealing with completely different types of development. One where there is time, thought and money investing in the home and another where most of process has been removed from the end user. In our convenience society it is no wonder that most people live in the latter type of property. However, if you talk to people about their ideal home, most would talk about building their own homes that meets their requirements, aesthetic values and standards. So why don't we encourage self building?

The advantages of self building in Wales is especially important for the overall construction industry. Wales desire to be ahead of the game when building 'Low' carbon homes means that there is a need to embed skills and knowledge in companies. Major house builders cannot do this, as they only use small numbers of architects, designers and contractors, whilst more individual projects would help bring these skills to lots of smaller companies. So there is an industry argument for encouraging smaller companies to be involved more.

The major advantage, though, is that by allowing people to build their own homes, they will also build a more stable community. When there is buy-in to an area people will have more emotional and social links to the development. People will therefore look after the area as they have pride in it and also their home-for-life based in it. If a house is just another step up the property ladder there are fewer emotional ties to the building. This is probably the reason why new housing developments are seen as soul-less dormitory zones without any sense of community. Trying to create a sense of community by providing facilities like community and shopping centres is generally not very successful as there is no history of community in these newly created places. Communities are strange and mobile things that are notoriously difficult to define, but when they arise it tends to be driven by factors like: history of place and family; slow development over time; sense of belonging from residents; a level of social energy from residents to create change or maintain the status quo. So given that community is a social phenomenon, having a stable and committed population in an area are really important factors towards creating one.

The current Housing Minister is very supportive of self building, but the systems that exist in Government for disposing of land from public bodies is too restrictive. The system needs to be looked at to see if it would be possible to dispose of land in smaller plots to give people a chance to buy them. Most land sales come with some sort of master plan and / or conditions of sale, so in theory it should be possible to ensure that there is a percentage of land that is put over for self builds / co-housing projects etc. These slight changes might be a pain for the larger house builders, but it would make for better communities, more varied places and also help keep house values in the area.