Where your water comes from decides what is likely to be in it, and therefore how it should be treated. Mains water arrives already treated; a borehole brings up minerals from deep rock; a spring or stream reacts to every rainstorm; a caravan tank depends on how it is filled and stored. Choose your source below for a guide to its typical problems, the rules that apply and the treatment that works.
Where does your water come from?
Mains water
Treated by your water company. Issues usually come from your own pipes: lead, chlorine taste and hardness.
Mains tap water →Borehole
Deep groundwater, often rich in iron, manganese and hardness; bacteria risk depends on the headworks.
Borehole water →Well
Shallower than a borehole and more exposed to surface water, especially older dug wells.
Well water guide →Spring
Shallow groundwater that responds quickly to rain; often acidic and at high risk of bacteria.
Spring water supplies →Stream, river or lake
The highest-risk source: heavy sediment, bacteria and parasites. Needs robust treatment.
Surface water →Rainwater
Ideal for toilets, laundry and gardens; needs filtration and strict separation from drinking water.
Rainwater harvesting →Caravans, boats and off-grid
Tanks and hoses are the main risk. Simple filters and good hygiene go a long way.
Off-grid and mobile water →Water sources compared
| Source | Most common issues | Bacteria risk | Typical treatment |
|---|---|---|---|
| Mains | Lead pipes, chlorine taste, hardness | Very low | Drinking water filter, RO, softener |
| Borehole | Iron and manganese, hardness, H2S | Low to medium | Iron filter, softener, sediment, UV |
| Well | Bacteria, nitrate, iron | Medium to high | Sediment, specific treatment, UV |
| Spring | Bacteria, acidity, turbidity after rain | High | pH correction, sediment, UV |
| Stream, river, lake | Sediment, bacteria, parasites, colour | Very high | Settling, bag and staged filtration, UV |
| Rainwater | Debris, bacteria from droppings | High (non-potable use) | Self-cleaning filters, UV for higher-grade use |
| Caravan, boat, off-grid tank | Stale tastes, biofilm, chlorine | Depends on storage | Inline filters, gravity filters, 12V UV |
These are typical patterns, not guarantees. Every supply is different, which is why treatment should always be designed from a laboratory water test.
Which rules apply to your source?
- Mains water is the responsibility of your water company up to your boundary. Plumbing and appliances must meet the Water Supply (Water Fittings) Regulations 1999.
- Boreholes, wells, springs and surface water used for drinking are private water supplies under the Private Water Supplies (England) Regulations 2016. Shared and commercial supplies are monitored by the local authority; see our regulations guide.
- Taking more than 20 cubic metres a day from groundwater or surface water in England is likely to need an abstraction licence.
- Rainwater and other alternative supplies must be kept separate from mains pipework, labelled, and notified to your water supplier.
Wales, Scotland and Northern Ireland have their own equivalent regulations.
Next steps
Find out what is in your water with our drinking water testing guide, look up a specific problem in water contaminants explained, or ask our team. Wrekin Water is a family run company based in Bettisfield, Shropshire, serving more than 50,000 customers over 15 years and rated Excellent on Trustpilot.