Rainwater harvesting - do you do it?

Building or renovating is the ideal time to think about installing a rain water collection system. There are numerous benefits to be had from using rainwater; its natural softness means less detergent as well as lower limescale build up on appliances. People with sensitive skin often experience less irritation and gardens will also benefit from the natural properties of rainwater. Having your own supply means that you can avoid the hassle of hosepipe bans; this is often a big consideration for homeowners with thirsty vegetable patches and swimming pools. Plus with prices continuing to rise, there are big savings to be made!

Water can be harvested in three main ways, the best known and simplest method is the good old fashioned rain butt. You can now buy a simple connection system which allows two butts to be linked together and filled one after the other. This minimises any waste. Alternatively an internal reservoir can be sited in a cellar or outbuilding. This is more expensive than the simple rain butt method but will allow enough water to be stored for domestic usage such as washing machines and toilets as well as exterior and garden use. The third method involves sinking a giant reservoir into the ground outside. The huge advantage of this system is the large volume of water that can be stored - up to 9000 litres! These tanks need to be sited at least a meter below ground, in an area where there is no vehicular traffic and away from any tree roots which might cause damage, so installing them at the same time as the ground works are being done, will reduce installation costs. Any system other than just storage, requires a pump and the pump size (and cost!), will depend on the household size, garden size and water requirements.

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Three 500 litre water butts cut my water bill in half. It is still too high, so I am looking at getting another water butt or two.

We looked at rainwater harvesting when we were making our plans for our renovations. We had decided on geothermal heating for the gite and the swimming pool and when the wells were being sunk they came across a very good supply of underground water. We decided to go for a forage instead of rainwater harvesting, as you do need rain to top up your supply and 20,00 litres does not go far when you have a large potager and an orchard.

It did cost more but we are confident that we can keep our veg alive and top up our swimming pool, which we did successfully within the terms of the arête.

Yes in my cellar. Spent the whole day mopping it out!!!

The point James makes 'Water will become a precious commodity' is no joke. We can say what we like about the rain but today we stocked up on large bottles of drinking water. Why? There were two sogedo vans about this morning. One stopped and asked if we are on main sewage. Nobody is here, but I guess they had to ask.

When I went out and was looking at fields below us I saw the amount of dirty 'foam' was clinging to everything, also detritus everywhere. Presumably the sogedo people were looking for where something else (all guess) was coming from. Ground water, albeit almost in the Dordogne here, is obviously polluted. So too, presumably the sources for mains potable water. The more polluted sources are, the harder it is to 'purify' tap water. With climatic change, despite politicians lining up to deny it exists, scientists have already warned about that some years back and newer predictions get less cheery.

We have one of those cubes that I bought from a neighbour for €30 when he moved away. That is all, but we have the well that does not (so far) dry up and we would like to be able, money willing, to use that for as much as possible, then harvest water after our bac degraisseur instead of letting it go to the ground for the vegetable garden and flowering plants. A dry toilet too.

No chance of a big tank though, not a good economy for us and the work with solid rock at deepest a metre down but up to the surface in too many places would be horrendously costly. So we can wish, but...

Our neighbour has linked up 3 x 5000 litre and one 3000 litre concrete tanks but he has the advantage, bearing in mind the terrain is rock, of having a shallow steep drop on one side of his land so he has no need to dig a hole. The water in our tanks are not for drinking they are for toilet flushing, washing machine and garden use.

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When we built our Passif house in the Lot, we included rainwater harvesting fed from the roof. By far the best value solution was to use septic tanks, we opted for 3000 litre concrete ones linked in series, and these cost 360 euros each in 2012, after some shopping around, through the local groundworks contractor who was much cheaper than the builders merchant. One important point though: Not all septic tanks are guaranteed to be watertight! Can you believe that?. So make sure the model you choose IS. Burying them avoids the problem of freezing in winter, so the water can be used to flush the toilets all year round, and we simply grassed over the top so they look like lawn.

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It is expensive but my husband has installed two F-line interconnected 7500 litre tanks in the ground at our new build house. We bought the tanks in the UK, had them delivered to a haulage company in Salisbury who delivered them to our property in Lot et Garonne. Our neighbour helped us unload them with his forklift and my husband put them in place with a large digger. All the equipment was bought in the UK too, but, all of it can be supplied by French companies. This was in September 2013, by November 2013 they were overflowing - so he is now thinking of getting an additional another ...............

Just to throw in a bit of "anti green" propaganda. This is because I just loathe being ripped off no matter what the ideology. A septic tank of 3000 litres cost around 600 euros....so why on earth does a water reservoir of smaller dimensions and capacity cost nearly twice as much??? Doesn't make sense at all. My remedy to this conundrum would be to install a septic tank instead...simples!! ;o))

Just come back from Lidl doing my eco shop, bought 2ltr bottle of spring water for €0.17 thats 2500l for €212.50!!!

Agreed; but we are being exploited by the green sales pitch; it shouldnt cost €1100 odd to collect that amount of water. You would only see a minimum payback over 25 years.
When are we going to get off our guilt trip. By moving to France we immediately gained lots of brownie points by having 85% of our electricity produced by nuclear…Zero Carbon and a lot cleaner than coal and I include nuclear emissions in this.
So called green solutions leave everything cosy except your wallet. The cost of solar water panels exceeds belief and as for heat pumps and underfloor heating costs dont tell me its because its new technology, 20 years ago I noticed heat exchangers on the roof of the Greek holiday complex I stayed at. What is the energy cost of the manufacture and distribution of this equipment?
Looks like the redundant double glazing sales team have discovered green. We shouldnt encourage them, has anyone out there come up with a cost effective method of using green technology that doesn’t turn your environment into Steptoe’s Yard?
I heat my well insulated home by wood, lower cost, zero emissions, great toast and helps the local economy, a win win position. What else do other members do?

There is an environmental consideration though. Using drinkable water to flush toilets is a shocking waste of resources. Water will become a precious commodity before long and we’ll be left wondering why we squandered it IMO

You take my point tho’ its warm and comfy to be green but at the end of the day if it dont pay…

About 3 days in this part of the world given our current amounts of rainfall…

as a person fast approaching his dotage, I considered rain water collection amongst other ‘green’ issues while i was specifying my new build.
it didnt cost out.
1 cu metre of water costs €1.46 here, the picture you use as a header offers 2500 litres for €1150 or circa 50c per litre, as you will refil this a couple of times a year what is the payback period against mains water?

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Hi Ilike your site we have a house in france with water issues. We have a big roof, many collection outlets and plenty space under the house with good head height (cave). Our address is Bieysse no Vabre our post code is 81330 Tarn

My mobile number is [0044 (0) 7810 541 463](tel:0044 (0) 7810 541 463). I am in France until the 28th April 2019.

We are in an urgent situation to investigate systems price and earliest installation date.

Please contact me as soon as possible

Many thanks

Best regards

Mike Stripling

We are available at any time to take a call or meet if possible nd have full access to internet and email.

Hello Mike and welcome to the Forum

What is your “urgent situation” ???



The problem is its economically unviable in most houses to retro fit either grey water recycling or rain water harvesting for internal use. Suddenly its new tanks - new plumbing and a monumental pain. New builds you’d be a bit dumb not to at least consider it. In an ideal world we’d have gone three massive tanks and run everything off rain water

Outdoors - we’re slowly building our capacity -although given gutters seem to fall apart every month and rainfall has been tiny this years been disastrous

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After a blazing day… it’s chucking it down… I have lots of water captors dotted on the terrace and use these to fill the watering cans… for use in drier spells.

I have been thinking of buying a water-butt, just a question of finding the right spot to place one…


We inherited these three in-line plastic tanks that catch run-off from the asbestos roof of a garden store. They fill up surprisingly quickly when it rains Normandy-fashion, but for the last three years it hasn’t, it’s sec sec sec according to my nextdoor neighbour and climate guru.

The water grows algae and isn’t potable but is very useful for watering the potager, and a good stop-gap standby for other domestic use if the supply fails. The chickens prefer it to tap-water which they disdain.