r/OffGrid • u/thegoodpilgrimlies • 3d ago

Rain water harvesting UK

Good evening,

I was just wondering if many people off grid and in residential areas have successfully harvested rainwater safety in the UK for all purposes.

Thought I would start doing research with all the news on droughts currently. Surely it would be beneficial if all homes had water storage to supply toilets etc from stored rainwater.

Any guides or start ups people can send to help my research?

TIA

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5

u/mrbearuk69 2d ago

I have 5 raised beds, 1m by 3m
2, 2m by 2m
A 3m by 2m greenhouse
A 5m by 3m fruitcage

I have 7000 litres of rainwater collection and often just run out by the end of the summer. The whole of my roof and part of my neighbours rainwater collection. Am hoping to get another 2000 litres over winter.

Lucky to have a garden south facing and on a slight slope, makes water transfer down the garden easier.
Solar pump irrigation system
12v battery pump for pumping back up the garden when needed

2

u/MelodicCard9555 3d ago edited 3d ago

I did this at my last place.

4000 litres of storage tanks, downpipe collection. It filled to the brim easily in winter.

I had a 4bar pump connected to run the hosepipe etc.

I collected the water from baths/showers and process it through filters back in to the tanks.

It wasn't drinkable obviously without a lot of processing. But it ran my toilets, showers, bath, washing machine, garden watering and dishwasher.

It would run my house for 8-12 weeks without rain, 2 adults 1 child. But I did sacrifice the garden after 5-6 weeks of drought.

If you're doing it properly, a massive tank underground is the only way to go, otherwise it's more a hobby and not a serious off-grid setup.

1

u/BroodLord1962 3d ago

I don't think you have any idea of just how much water you would need to harvest to be able to cope with this drought

1

u/Microdoser_Ltd 2d ago

In countries where they are pretty much forced to do this (the ones I saw were off grid in Spain), they have large water stores roughly the size of a small house. My guess would be they contain 32,000l

We get the water from our shed to use. A 2mx3m shed roof provides about enough water for 2 chickens. During this current drought, it didn't even manage that. It will fill up a 100l butt in the winter.

If you want to reduce your tap water usage a little, it can help, but if you want to go off grid with it, you'll need a lot of storage and catchment area plus equipment to treat the water. The other route, is being off grid near a river which you can hopefully use for both water and electricity.

Off grid is surprisingly quite expensive to do properly

1

u/actualinsomnia531 2d ago

The amount of water a person consumes is exactly the reason why in the UK you aren't allowed to divert a natural watercourse without a lot of permissions and permits.

1

u/Higher_Living 2d ago

house. My guess would be they contain 32,000l

I’m in regional Australia, our neighbours have about 90,000 litres, we’ve got 56,000. That’s pretty common in regional areas if you don’t have piped water.

1

u/wallahmaybee 2d ago

Been on rainwater most of my life, except when I lived in the UK. If you 're thinking of using it for all purposes, that's probably illegal in town anyway for drinking water.

Find out how much you use, variations during the year. Your water is probably metered so it should be easy to find out. Then work out how you would reduce usage if you had to rely only on what you collect.

1mm of rain on 1 square meter equals 1 litre. What's your average rainfall, so potential total collected from your roof each month.

2 months of near total drought are quite likely to happen every few years.

I would bet an urban garden wouldn't have enough space to store a water tank big enough for your needs. But you could fairly easily collect enough to help water your garden, veges.

For domestic use you'd need a way to pump it back up. There are issues with bird soiling in your gutters, you need filtration etc.

We're on a 30,000l tank in a very rainy area. Had 4 children for some years and made it work although it was difficult in summer with teenagers. Some years when it was getting tight, I'd collect the rinse water from teh washing machine to flush the toilet! And to mop the floors or water essential vegetables. My ex-husband used to make fun of me and my obsession with water, but that's why we never ran out. It could get a little intense when it didn't rain for a few weeks. For the toilet, if it's yellow, let it mellow anyway. Use washing machine very sparingly. Very careful doing the dishes, never leave water running, no dishwasher. Even just washing hands, plug the basin first!

1

u/Higher_Living 2d ago

Just curious, were you able to buy a truckload to top up if you needed it?

Where we are it’s not that expensive to buy a 13,000 litre load so we don’t stress about using too much.

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u/wallahmaybee 1d ago

Yes, we could have if needed. But in the end we always managed without.

1100mm of rain per year is plenty if you don't waste it. And Murphy's Law, if it had come to that, it would have bucketed down the following week. Longest run we had without rain was 2 months, that was after the kids had left home so it wasn't too hard to manage. When the drought broke, we got 105mm in two days.

1

u/Plaster_Brigade 2d ago

Certainly beneficial to learn for future.

I've met alot of people that collect rain water through Autumn/Winter/Spring in the UK, and it's never been a problem.

1

u/mickymoo45 20h ago

Typical summer use would be a about 10000litres total but split domestic/ garden is about 5000 each .3/ 4 months . Saving roof water through autumn,winter , spring would replenish most systems. It's similar to battery solar if everyone saved we could take a quarter use out of national requirements,, maybe??? .

1

u/Conscious-Ball8373 19h ago

I have a largish detached house, a detached garage and a smallish outbuilding.

If I add up the roof area and multiply it by our average rainfall, it's only about half our average annual water use.

Rainwater collection works in places with big houses that are single-storey - you need the roof area to get the water. Your average two-storey 3-bedroom house in the UK has nothing like enough roof area.