Off-Grid · Water
Water: Wells, Rain, Borehole — or Just the Mains
"No mains water" sounds like a dealbreaker; out here it's often the opposite. But there's a trap in it too — the dream of drilling your own borehole can cost you thousands, need hundreds more in checks, and still come up dry. So this section does the one thing the drilling firms won't: it puts the four ways to get water side by side, with the real cost of each over 5, 10 and 20 years for a one-person setup.
There are four honest routes: an existing well or spring, rainwater, a drilled borehole, or a mains connection. The right answer is usually decided the moment you buy the plot — so knowing the costs before you offer is worth real money.
The headline most people get backwards: a mains connection is often cheaper than a new borehole — and an existing well beats everything. A borehole is the expensive gamble, not the frugal off-grid dream. Do the homework before you drill, not after.
The four ways in cheapest first
Each has its own guide — the detail, the method and the pitfalls.
The jackpot — often already on the plot. Drop a pump in and you have water on day one. How to bring one back into use and test it.
The well & spring guide →🌧️ Rainwater harvestingCheap, simple, legal for the garden, the loo and washing. Roof, tank, first-flush and pump — the obvious first system to build.
The rainwater guide →🕳️ A drilled boreholeThe last resort, and the money-pit if you rush it. Why the homework matters more than the drill, and what it really costs.
The borehole guide →🚰 Making it drinkableAny source can be made safe — test first, then filter and UV. What's in the water, and the kit that fixes it.
The treatment guide →The real cost over 5, 10 & 20 years one-person setup
Indicative GBP for a frugal one-person off-grid home — a shape to reason with, not a quote. Pump power comes off your solar, so it's counted as near-free.
| Option | Upfront | ~5 yrs | ~10 yrs | ~20 yrs | The catch |
|---|---|---|---|---|---|
| Existing well / spring | ~£750 | ~£1,100 | ~£1,800 | ~£2,850 | Only if the plot has one. Cheapest by far. |
| Rainwater | ~£1,750 | ~£2,400 | ~£3,400 | ~£5,050 | Needs roof + storage; may not cover a dry summer alone. |
| Mains connection | ~£2,000* | ~£3,250 | ~£4,500 | ~£7,000 | *If the main is close. Ongoing metered bills — but no gamble. |
| New borehole | ~£8,000 | ~£8,700 | ~£9,850 | ~£11,700 | Dearest at every horizon — and it can come up dry. |
Read the columns across: over any period, an existing well wins, rainwater is cheap, mains is moderate — and a new borehole is the most expensive option there is, before you even count the risk of drilling a dud. That's the whole argument for doing your homework first.
Why the borehole is the trap homework before drilling
£1,000s to drill, £100s in checks — and it might be dry
A borehole isn't just the drill. Before it's usable you're paying for siting advice, a flow test, a potability test and treatment — hundreds on top — and the drill itself is sunk cost whether or not you hit good water. Rush in and you can spend £8,000 to learn the yield's too low or the water's foul. The borehole guide is mostly about the homework that stops that happening.
So compare it honestly against the mains
Before you romanticise drilling, get the Enedis-style equivalent for water: a written mains-connection quote. If the main is anywhere near the plot, a connection plus twenty years of a frugal one-person water bill often comes in well under the cost of a borehole — with none of the risk. Off-grid by choice, not by an expensive accident.
And check for a well before anything
None of this matters if the plot already has a well or spring — which, in granite country like the Morvan and Limousin, many old houses do. It's the first thing to look for and the cheapest water you'll ever have.
The one rule for all of them: test before you drink
Garden water is easy; drinking water is where you don't cut corners
Well, spring, rainwater or borehole — any of it can be perfectly good or can carry nitrates, bacteria or run-off. The rule never changes: test it, and treat it if it needs it. Never trust a picturesque source just because it looks clean.
The water source is a make-or-break detail
A well on the plot, or a main at the boundary, changes the whole sum. It's exactly what the free desk routine flags before you ever drive out.
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