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Water from a borehole or well is never “ready to use”: sand, iron, limescale, bacteria… the problems depend on the aquifer. This guide helps you choose filters, a water softener or ultraviolet treatment in the right order, and explains why everything starts with a water analysis.
Start with a water analysis
Choosing a treatment without knowing the water is guesswork. A laboratory analysis shows what your water really contains (suspended solids, hardness, iron, manganese, pH, bacteria…) and which uses it is or is not suited for. Repeat it if the water changes in appearance, smell or taste, or after work on the borehole or well.
Drinking water: no equipment can be presented here as making water fit to drink. If the water is to be drunk or used for cooking, ask a professional (installer, laboratory) and check the regulations that apply to your borehole or well (declaration to the town hall, permitted uses).
Which problem, which solution?
| Finding | Possible cause | Equipment to consider |
|---|---|---|
| Cloudy water, sand, deposits | Suspended particles | A sand filter or cartridge filters first |
| Orange or black stains, metallic taste | Iron, manganese | Filtration suited to the measured level: see the water treatment equipment and ask for advice |
| White deposits, scaling, soap that barely lathers | Hard water (limescale) | A water softener or a scale inhibitor |
| Doubts about bacteriological quality | Micro-organisms | An ultraviolet steriliser, after filtration |
| Drinking water to refine | Dissolved salts, taste | An reverse osmosis unit at the point of use, on professional advice |
The equipment, in the right order
Order matters: each stage protects the next one. Filter first, then treat.
- Sand or cartridge filter (first): it holds back particles. A sand filter suits large volumes and is cleaned by backwashing, depending on the model; cartridge filters are simple to maintain, and cartridges are replaced or washed depending on their type.
- Water softener: resins retain limescale and are regenerated with salt. It protects water heaters and appliances. Softened water contains more sodium: ask for advice before drinking it.
- Scale inhibitor: it limits limescale deposits in pipes without necessarily removing the limescale from the water, depending on the model’s principle.
- Ultraviolet: the lamp acts on micro-organisms as the water passes. It needs clear water (filter first), removes no dissolved substance and is replaced as set out in the manufacturer’s manual.
- Reverse osmosis unit: for a small flow at the point of consumption, never to supply a whole house.
Sizing, avoiding mistakes and choosing
A filter must accept your pump’s flow rate (1 m³/h is about 16.7 l/min). An undersized unit restricts the water, drops the pressure and clogs quickly. The product page gives the maximum permitted flow. To estimate your needs, see the indicative flow rate / pressure table.
Fit a pressure gauge before and after the filter: a growing difference signals clogging. A well-adjusted tank also steadies the whole system, see our guide /en/content/23-choosing-a-bladder-pressure-tank.
The mistake to avoid
Fitting a UV unit or a softener straight at the pump outlet, with no filtration and no analysis. Water full of particles fouls the lamp and clogs the resins, and you believe the water is treated when it is not. Poorly chosen equipment is expensive and gives a false sense of security.
Our 6-step selection method:
- Have the water analysed by a laboratory.
- Define the use: watering, bathrooms, appliances, cooking or drinking (professional advice for drinking).
- Note your pump’s flow rate and working pressure.
- Fit filtration first, sized for that flow.
- Add the targeted treatment according to the analysis (softener or scale inhibitor, ultraviolet…).
- Plan the maintenance (cartridges, salt, lamp) following the manual, and test again if in doubt.
Frequently asked questions
Do I need a water analysis before installing a treatment?
Yes, it is the first step. Without it you know neither what has to be removed nor whether the water suits its intended use. A laboratory will also tell you whether further advice is needed.
Water softener or scale inhibitor: which one?
A softener retains limescale with resins regenerated with salt; a scale inhibitor acts on deposits without that kind of upkeep. The choice depends on the water hardness, the use and your budget: check the product page or ask for advice.
Does ultraviolet treatment make water safe to drink?
We cannot say so. Ultraviolet acts on micro-organisms, but not on dissolved substances, and it relies on clear water. For drinking water, ask a professional and follow the regulations that apply.