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Q&As
What are the best rainwater harvesting options for those without mains water?
We are in the process of self building a 18x12m steel-frame barn conversion. We are very interested in harvesting as much rain water as possible, as we do not have a mains water connection. We may use a borehole but could we use treated rainwater? Who can we talk to about this?
2 Answers
Hi Denise,
Thank you for your question. We are reaching out to our experts who will hopefully provide a helpful answer for you.
Best wishes,
Elinor
The water collected through rainwater harvesting (RWH) solutions is typically used for non-potable (non-drinking) purposes, including WC flushing, washing machines and watering the garden. This type of water usage accounts for roughly more than half of domestic consumption, so it’s probably worth investing in rainwater harvesting – top UK companies for this include Rainharvesting Systems, Stormsaver and Total Water Systems.
Water used for drinking, cooking, washing up and showering, however, must be potable. And as harvested rainwater contains significant contaminants – made worse during storage – more advanced rainwater harvesting techniques are needed. Fortunately, there are now systems available that clean rainwater to a drinkable standard, using a combination of micro- and carbon filtration, reverse osmosis and UV disinfection.
Freeflush, for example, puts together a series of filtration systems (e.g. Ozo-Pure) which sanitises rainwater to potable quality and can even purify water from a borehole if necessary. There’s also a Dutch company – Drop2Drink – which sells a system licensed for use in Belgium and Holland which delivers up to 30 litres/minute of potable water, more than enough to cover domestic demand. Although, it is not yet set up for the UK market.
With any of these systems, there is a significant capital outlay required, but it is likely to be much less than getting mains water to an off-grid site. It will be essential that any potable water supply is regularly tested and complies with the UK Private Water Supply Regulations 2016.
Nigel Griffiths, Build It’s sustainability expert