Content supplied by Rainwater Harvesting
I am writing this on Monday 16th July 2018. The date is important because I have never known a time when it hasn’t rained for over six weeks. So what will happen next?
We have been advised to use water sparingly and our water providers are doing an amazing job. Water supply will not suffer unless the UK has a dry winter and that could then cause problems. The concern is the prediction of torrential rain and thunderstorms. Dry parched land that does not absorb rain well running into the drains and rivers at a significant rate. This can cause the ‘F’word. Floods.
So from one drama to another.
Thankfully there is a long term sustainable solution. The answer is collecting fast flowing rainwater off the roof and storing in an underground tank. Rainwater harvesting has been around for thousands of years but it was the Victorians that engineered our incredible water network which meant for 100 years that water supply was cheap and plentiful. However with aging pipework ,population growth and changing climate there has to be a rethink for the future. Rainwater can be used for any non-potable application such as toilets, washing machines and outside use. There is no need to flush the loo with drinking quality water bought from miles away. As the water does not contain any chemicals it is better for the washing machine and kinder to plants. As part of the British Standard rainwater harvesting tanks are sized with the prediction it will rain within 21 days in the UK. However it does appear that we are tending towards longer periods of dry with heavier downpours. The means that the average rainfall doesn’t change dramatically but it would be helpful if as much as possible could be harvested while it is raining. Typically tank sizes vary between 3000-7500 litres for a domestic property. Our preference is for shallow dig tanks which are between 1-1.5 metres in depth so easier to install and can be used with high water tables. Before the water enters the tank it is filtered of leaves and other debris. The harvested water is from the roof only and through a closed system so that surface water contamination keeps the water fresh. They are underground ,not only as they take up a big area (and some would say not the prettiest things to look at) but temperature variances are reduced and no light pollution. A harvesting system would help relieve long term stress on the supply of water but in this unusual year it may now require to turn onto a mains top-up. Rainwater Harvesting Ltd design and manufacture systems in the UK for UK homes.
There are two types-Direct feed Back Up In A Box. Every time the toilet flushes the pump runs. In this system should rainwater become critically low a small amount of mains will be introduced into the underground tank. This is all done automatically so that the homeowner does not need to do anything.
The second type is a gravity fed system-The award winning Rain Director. Rainwater is pumped up to a header tank in the loft space and the toilets are fed from there. This system costs about 1p/per person/day and if rainwater becomes low in the harvesting tank then 100 litres of mains water is fed into the header tank. So economical on power and mains water.
Over the previous years it’s not been supply but flooding that has been highlighted.
At RainWater Harvesting Ltd we came to the conclusion that there is a common factor-too much or too little rain. So as well as collecting water to use at source why not also collect more to prevent it overwhelming the system. The term used is SuDS (Sustainable Drainage System). Many planning applications stipulate that discharge rates off the land are the same as before the building takes place. Once again it can be the fast flowing roof water that overwhelms the soakaway. Our innovative RainActiv combines the benefits of rainwater harvesting with a SuDS solution. The lower volume of the tank is for harvesting purposes but there is extra volume to collect further storm water. The SuDS element is then released at a controlled and calculated rate leaving room for the next downpour. Using Micro Drainage software we can calculate the extra capacity required with drainage rates as low as 0.05 litres/second.
In conclusion as a long term water solution look to the past to take care of the future.