This September may have been the driest since UK weather records began, but the rain-dance was called off this week when we were inundated with autumn showers. Excitingly, we are now about a month away from completion of our eco build project. This week saw the delivery of our rainwater harvesting (RWH) tanks, monster great containers that will help us save water by reducing our use of potable mains supply by at least 50%. We have two collection tanks: a 7,500 litre house system to store rainwater run-off from the roof, to be used for flushing loos and the washing machine, and a second 5,000 litre garden tank for maintaining the levels in our two ponds and for general garden use, such as watering and washing the car…and our dogs.

According to South East Water, un-metered customers in our region consume on average 160 litres of water per person per day, the equivalent of taking two baths. Based on this, a person could use an average of 58,400 litres of water each year.

The benefits of a rainwater collection system are:

  • To preserve groundwater supplies
  • To counter rising water and waste costs
  • To relieve sewage treatment systems and the strain on the sewage network

It makes so much sense to harvest the natural resource of rainwater for WCs rather than using potable mains water, don’t you think? When you spend a penny at Skyhouse, you too can feel a ‘flush’ of pride in our water-saving loos.  

The system, using Graf RWH tanks from Germany, was supplied and recommended by Chandlers Building Supplies through its Sustainable Building Solutions division based locally here in Lewes. So how does it actually work? The rainwater is filtered going into the collection tank and then extracted from the tank just below the surface where the water is cleanest. For washing machine use, an inline filter is used to take out any remaining small particles. The house tank has a sophisticated system of float sensors and an automatic switch to the mains if the rainwater level drops below a certain depth. The garden tank, installed on higher ground behind the house, operates by a gravity feed down to the ponds in the front garden.

Based on the average non potable water consumption (washing machines, loos, irrigation, car washing etc.) of a 5 person household, the vast 7500 litre house tank has been supplied to hold enough water for 18-20 days without needing to empty the tank too often during dry periods. With such a large tank, we will be able to collect more of the yield from the roof making it less likely that we’ll have to switch to mains water due to the tank emptying.

But what if we have a very wet period and the capacity of the two collection tanks is exceeded? To cope with potential overflow, Joe and his team have created a huge 2.4m3 soakaway hole (2,400Ltr) down at the front of the Skyhouse plot, into which are submerged 95% void ‘Polystorm’ crates to prevent any land slippage. Any surface run-off coming down the driveway will be directed into this hole by the grating across the front entrance.

If you would like to use less water at home and in the garden to really make a difference, here are 10 top tips for water saving from South East Water

  1. Put your fruit and vegetables in a bowl to wash them instead of leaving the tap running.
  2. Use that bowl of water to water the garden.
  3. Remember that dishwashers and washing machines are water efficient only when they are full.
  4. Dripping taps mean a big waste of water, up to 100 litres a week, so now’s a good time to fix that leaky tap.
  5. Just taking a shorter shower instead of a bath will save a significant amount of water.
  6. Ask your water supplier for a shower timer and see if you can meet the 4 Minute challenge.
  7. If you enjoy a bath, just try running a few centimetres less, your soak will be just as relaxing.
  8. A flush saver bag in your loo system will really reduce the amount of water used.
  9. In the garden you could install a water butt to collect rainwater.
  10. Water plants using a watering can, always water early in the morning and after sundown to avoid evaporation, and always water at the root, avoiding the foliage.