Water filter type
Sediment filters
A mechanical filter that captures sand, silt, rust flakes, and other particles. Often the cheapest thing that fixes a visible problem, and a required first stage ahead of most other equipment.
The cheapest fix in water treatment
A sediment filter is a mechanical screen. Water passes through a pleated or spun cartridge with a rated pore size, and particles larger than that rating are held back. There is no chemistry and nothing to exhaust in the way carbon exhausts.
It is frequently the only thing a property needs. Grit in the aerators, a gradual loss of flow, cloudiness after work on the mains: all of these are particulate problems and all of them respond to a filter that costs very little.
It is also the first stage in almost every larger system, because a softener, a UV lamp, and a reverse osmosis membrane are all damaged or degraded by particles reaching them.
Micron rating and the staging trick
Cartridges are rated in microns. A lower number catches finer particles and clogs faster. Fitting the finest available cartridge as the only stage is a common mistake, because it blocks quickly and drops pressure.
Where there is a lot of sediment, two stages in series work better than one fine one. A coarse cartridge first takes out the bulk, then a finer cartridge polishes. The coarse stage protects the fine one and the pair lasts far longer than a single filter would.
Spun polypropylene cartridges are depth filters and hold more before clogging. Pleated cartridges have more surface area and some can be rinsed and reused, which lowers running cost where sediment is heavy.
Do the glass test before you buy anything
Fill a clear glass and let it stand on a worktop. If it clears from the bottom upward, that is air coming out of solution, which is harmless and needs no filter. If particles settle to the bottom, that is sediment and a filter will help.
If the water is cloudy and stays cloudy after several minutes, that is turbidity from very fine material and it needs a finer rating than a standard cartridge.
Understand that a sediment filter improves nothing you cannot see. Lead, nitrates, PFAS, hardness, and bacteria all pass straight through. It is a clarity and equipment protection measure, not a safety one.
What it reduces, and under which standard
Each row names the NSF/ANSI standard the category is tested under. A standard describes what the test covers. It does not mean every unit on the market carries that certification, so check the specific model against its listing before you buy.
| Contaminant | Standard | Note |
|---|---|---|
| Particulates and turbidity | NSF/ANSI 42 |
What it does not do
Every filter has a boundary. These are the things this one will not fix, listed so you can rule it out quickly if your problem is on the list.
- Anything dissolved. Lead, nitrates, hardness, and PFAS pass straight through.
- Taste and odour, which need carbon.
- Bacteria.
When it fits
- Visible grit or cloudiness at the tap
- You are protecting a softener, UV lamp, or RO membrane from fouling
- You are on a well with fine sand carryover
When it does not fit
- The water is clear and the complaint is taste or a health contaminant
- You expect it to improve safety, which it does not
Space, services, and upkeep
A single housing at the main line, about 4 by 14 inches.
No drain connection is required. It needs no power. This is not a rental option, because it fixes to the building and stays there.
Replacement interval. Cartridge every 3 to 6 months, more often after a main break or on a well with heavy silt.
Problems this is used for
We recommend this equipment against these confirmed problems. Each page explains how to confirm the problem before spending anything, and when treatment is not warranted.
- Iron and rust staining. Iron dissolved from rock or from corroding pipe.
- Sediment and cloudy water. Sand, silt, rust flakes, or air.
- Bacteria in well water. Private wells are not regulated the way public supplies are, and no one tests them but the owner.
Property types where this comes up
Common questions
My water is cloudy. Will this fix it?
Do the glass test first, because it costs nothing. Fill a clear glass and let it stand. If it clears from the bottom upward it is sediment and a filter will help. If it clears from the bottom upward as tiny bubbles rise to the surface, that is dissolved air, it is harmless, and no filter will change it. Air is very common after work on the mains.
What micron rating should I choose?
Lower numbers catch finer particles and clog faster. Fitting the finest cartridge available as your only stage is a common mistake, because it blocks quickly and drops pressure. Where sediment is heavy, a coarse cartridge followed by a finer one lasts considerably longer than a single fine filter, because the first stage protects the second.
Does it make the water safer?
No. It improves clarity and protects equipment downstream, and that is the whole of its job. Lead, nitrates, PFAS, hardness, and bacteria all pass straight through a sediment filter. It is frequently a necessary first stage in a larger system, but on its own it is a clarity measure rather than a safety one.
Other filter types to compare
If the notes above rule this out, these are the neighbouring options worth reading before you decide.
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