If you use a lot of water for your plot and don’t want to rely on the expensive mains supply, you might consider drilling a well or borehole. Wells are inexpensive provided the water table on your property is high and the water quality is good. Boreholes use exactly the same principle, but they are much narrower with an impermeable liner. This means you can drill down to a deeper aquifer, which cannot run dry and is less likely to become contaminated by surface water, sewage and so on.
The UK has been slow to introduce compulsory water meters, but the government is keen to see 80% of all households metered by 2020. This could prove expensive for homesteaders, particularly if they irrigate from the mains. Note that ground water is a renewable resource, but not an infinite one: you should still catch, store and use as much rainwater as you can.
At the time of writing (May 2011) costs are likely to fall between £5000 and £8000, but the borehole company’s estimate will give you a much better idea. The cost mostly depends on the result of the geological survey, because that will determine the likely depth and rock types of the hole. A pump is usually necessary to lift the water from the aquifer. If the pump ever fails your water supply will stop immediately, so a storage tank is a vital precaution just as it is for other forms of supply. If you are extremely lucky and drill into an aquifer which is under pressure, then you won’t need a pump and a storage tank is probably unnecessary. Other expenses may include an electric pump to lift the water out of the ground, a storage tank if you require one, and appropriate filters and/or UV steriliser if the water quality is not ideal.
Running costs are low provided you don’t insist on remaining connected to the mains water system, which can create additional expense. Modern borehole wellheads can be hidden away in an underground enclosure, and even if filters and/or a UV unit are needed, these are no bigger than a large fridge and can be sited in an outbuilding.
A new borehole, installed to a high standard using modern materials such as PVC and stainless steel should last a lifetime. Borehole installation is an area where contractors can cut their costs in ways that cannot be seen until much later, so the least expensive quote is not necessarily the best. Choose a contractor with a proven track record and a written guarantee. If they offer a maintenance contract it is likely that their work will be of a high standard.
Ground Source Heat Pump installations also need a geological survey and can be vertically installed using a borehole. If you are considering a vertically-installed GSHP you can investigate the very efficient open-loop type installations, which can be used for drinking water abstraction as well as offering free heat.