Off-grid water in Spain

Start here: water for an off-grid home in Spain

Water is the system I’d check first on any off-grid property, because it’s the one you can’t buy your way out of quickly. Panels arrive in a week; a borehole permit can take months, and a dry well can’t be fixed at all. This page is how I’d think about it.

1. Work out how much you need

A household uses roughly 150 litres a day for showers, cooking and laundry, before the garden. That’s over 50,000 litres a year. A 100 m² roof in a dry part of Spain realistically gives about a third of that. My rainwater guide shows the sums.

2. Choose your sources

Most off-grid homes combine two or three:

• Rainwater into a tank: free once it’s built, but seasonal. A fitted tank costs €1,500–€7,000, around €2,600 on average.
• A borehole: the closest thing to independence, at €1,800–€15,000 depending on depth and ground, and it needs permission. Read borehole permits in Spain before you drill or buy a plot that relies on one.
• Deliveries by tanker: about €190 per 10,000 litres, more if you’re far out. Water deliveries and storage tanks covers sizing and access.
• Greywater for the garden: it doesn’t add water, but it stretches what you have. See how I reuse my shower water.

Our own story went in that order. The old well on our finca was dry, so we started with a rainwater tank, greywater and deliveries, then drilled a borehole in summer 2025 with a 1.1 kW pump.

3. Make it safe to drink

Borehole water inland is often hard and high in nitrates, and tank water can pick up bacteria. Test before you drink, then treat for what the test finds: reverse osmosis is the usual choice, with UV where bacteria are a risk. My filtration guide goes through the options.

4. Power the pumps

Pumps are among the biggest loads in an off-grid house, and their start-up surge can trip an inverter. A soft starter fixed that for us: here’s how. Run pumps in the middle of the day when the sun is doing the work.

Water changes by region

Rules and rainfall vary enormously. In Murcia and much of Alicante, water is the constraint that decides whether a finca works; in Galicia it’s the easy part. Each region also has its own river basin authority, which is who you deal with for a borehole. The region guides name them: Andalucía, Valencian Community, Murcia, Castilla-La Mancha, Catalonia, Galicia and Extremadura.

What to check before you buy

• Is the well or borehole registered? Ask for the paperwork, not the seller’s word.
• Does it give water in late summer? Ask neighbours, not just the agent.
• Is there a share in an irrigation community? It can add real value, and it has annual costs.
• Can a tanker reach the tank? A 10,000-litre lorry needs a decent track.
• Is there room for storage? Tanks are big, and buried tanks need digging.

The directory lists borehole drillers and water tank and filtration firms by province.