Equipment
Most villas do not need "a filter". They need the treatment that matches what is actually wrong with their water, and one or two common problems are not filtration problems at all. Start from what you notice, confirm it, and only then look at a category of equipment.
June 19, 2026 · 8 min read
People usually come to treatment from a symptom: a stained basin, a cloudy glass, a shower screen that will not come clean, a smell from the tap. Each of those points to a different cause, and each cause has its own kind of treatment. This guide goes from the symptom to the category of treatment worth looking into. It does not cover which tests a laboratory should run, which is in our guide to testing well water, or how the stages of a whole-house system are arranged and sized, which is in our guide to whole-house filtration design.
Symptom → confirm → treatment
Each row starts from something an owner sees, tastes or smells. The middle column is what confirms the cause; the last is the purchase people most often make that does not solve it.
Treatment works by quite different processes. Sediment filters strain particles out. Iron removal changes dissolved iron into a solid and then strains that. A softener swaps hardness minerals for others. Carbon adsorbs taste and odour compounds. UV damages microorganisms so they cannot multiply. A membrane pushes water through pores fine enough to hold back dissolved salts. A single cartridge sold as an all-in-one does a little of one or two of these, for a small flow, until it is spent. That is why the first question is always what the water actually has in it.
A few simple observations sort many problems before any test. Orange marks in the toilet cistern from water that looked clear at the tap point to dissolved iron. White crust on a kettle is hardness, but near the coast a white residue can also be salt. A smell that comes only from hot taps usually starts in the water heater, not the well. A cloudy glass that clears from the bottom up within a minute is air, not dirt. Note where, when and on which taps you see the problem, take photos, and then confirm with a test of the raw water before anything is installed. Our guides to brown or orange water, hard water and limescale and sand or cloudy water explain the causes behind the three most common symptoms.
This is the one to be clear about before spending money. Salt in well water is dissolved, so it passes straight through sediment filters, carbon, iron media and softeners. A softener even adds sodium as it removes hardness. The treatment that does remove dissolved salt is reverse osmosis, which is normally fitted at a drinking-water point, produces a stream of reject water and needs pre-treatment. For a coastal well whose salinity is rising, the more important work is at the source: how hard and how long the well is pumped, and whether it is in the right place. Our guide to salty well water covers that side.
Water can be clear, odourless and pleasant to drink while carrying bacteria from the surface. The only way to know is a microbiological test. If it shows contamination, disinfection is the treatment category, usually ultraviolet light, which needs clear water ahead of it and leaves nothing in the water to protect the tank and pipes downstream. Disinfecting water from a well that lets surface water in treats the result and not the cause, so the wellhead seal and its surroundings should be checked too, as our guide to protecting a well from surface contamination explains.
Some symptoms are the well telling you something, and filtration only hides them. Sand that keeps coming after the first weeks, a sudden change in colour or taste after heavy rain, or saltiness that creeps up through the dry season all deserve a look at the well before more equipment goes in. An inspection of the well is the right first step in those cases.
Not every problem needs treating at every tap. Sediment, iron and manganese, hardness that damages heaters, and bacteria in water used for showering affect the whole house. Moderate salinity, nitrate or a taste you only notice in a glass may only matter where people drink, and are often handled at a single kitchen point. Choosing which problems belong where keeps the equipment smaller and the running costs lower.
Wells on the island often have two or three of these at once: iron with hardness, or sediment with iron and a bacteria risk. Then the order of treatment matters as much as the choice. Sediment comes out first to protect what follows, iron before a softener, and disinfection last on clear water. How those stages are arranged, sized and maintained is the subject of our guide to whole-house filtration design.
If something is wrong with your well water, send our filtration team a description of what you notice, a few photos, and any test results you already have. We will tell you which tests are worth doing before recommending any equipment.
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