The way we do our laundry, clean our dishes and hose down our cars all has a surprising and largely unnoticed impact on the climate – that’s the headline of a BBC article The hidden impact of your daily water use. Water management is a crucial issue if you are building an ecohouse.
Water affects our environmental footprint in four ways:
- How much water we use.
- How much pollution we add to the water.
- How much energy is used in the whole process.
- How we manage natural stormwater flows.
Water is a scarce resource. Even in a wet climate like Britain the amount of water we can access of drinkable quality is limited and in recent years there have been water shortages in many regions. In a dry climate like Australia or Africa the problem is compounded. So it’s really important to reduce water use wherever possible. There are simple ways to do this in a new-build home, such as fitting low-flow fittings and dual-flush toilets. And if you live in an area where water use is metered, this will help keep your bills lower too.
Sadly, a lot of the things we do with water in our homes adds pollutants of varying toxicity. Many cleaning and toiletry products contain chemical additives that get flushed down the drain. When we wash the car we send petrochemcial and other toxic residues into the stormwater system. And when we use chemical sprays or artificial fertilisers in the garden they seep into the water table. There isn’t a lot we can do about this when we design and build an ecohouse, but once a house is lived in the more conscious we are in what products we use the less load we will put on the waste water treatment plants and on the natural environment.
Mains water supplies require a huge amount of infrastructure to collect, purify and distribute the water to our homes, and to treat what we flush down the drain. When the water gets to our homes the biggest culprit is the energy we use for hot water systems. The BBC article quoted above suggests that about 6% of the UK carbon emissions relate to the water system, in the US it’s a little less at 5%. We can minimise this impact by harvesting rainwater or reusing greywater, which reduces the amount of treated water we need from the mains, and by installing renewable hot water heating systems. We can even capture some of the waste heat before it goes down the drain with Waste Water Heat Recovery systems.
This is one area of water management that, happily, is already common practice. It is often referred to as SUDS – Sustainable Urban Drainage Systems – and is essentially about making sure as much rainwater as possible is allowed to permeate into the soil on our site rather than flow into water courses and stormwater drains, and to ensure any runoff is not contaminated or washes away topsoil. New housing developments often include a SUDS pond, a landscape feature that fills with water during heavy rainfall, letting it soak away when its dry. A great example of this in practice is Village Homes in Davis, California, one of the earliest eco-developments.