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Last Updated on November 5, 2026 by Muhammad Toqeer
The most common mistake here is buying a filter that is too good.
A 1-micron cartridge on a well producing fine sand will polish the water beautifully for about four days, then restrict it. Pressure falls, the pump runs longer to make cut-out, and the household concludes the well is failing. The filter is working exactly as designed. It was simply the wrong rating for what is in the water.
So the first half of this page is not about filters. It is about finding out what you are filtering, because that is the decision everything else follows from — and it takes a jar and a day.
Which symptom brought you here?
Most people arrive at a filter page because of something the water or the pump is doing. A filter solves some of these and makes others worse.
| What is happening | Usual cause | Will a sediment filter fix it? |
|---|---|---|
| Grit in the aerators and toilet tanks | Sand or silt carrying through | Yes — this is the job |
| Pressure drops over days, recovers after a cartridge change | The filter is already too fine, or overdue | No — change the rating, not the cartridge |
| Pressure low all the time, no filter fitted | Restriction, setting, or well capacity. Low pressure on a well has its own list | No — and adding one makes it worse |
| Pump short cycling | Tank precharge or a restricted switch nipple. Short cycling comes first | No |
| Rust-coloured staining, no grit | Dissolved iron, not sediment | No — a sediment filter does not remove what is dissolved |
| Cloudy water that never settles | Very fine colloidal clay | Rarely — needs far finer treatment than a sediment filter |
| Booster downstream keeps clogging | Sediment reaching equipment. Sediment clogging a booster | Yes, if placed correctly |
| Water suddenly turned dirty after years clear | Something changed in the well. Water in the well pit and casing faults come first | No — find the cause first |
Four of those eight rows say a filter is the wrong answer. That is worth knowing before you spend anything, and it is the reason this page starts here.
How do you find out what is in your water?
Fill a clear jar from an outside tap, ahead of any filtration you already have, and leave it undisturbed for a day.
| What you see after 24 hours | What it is | What it means for the rating |
|---|---|---|
| Grains settled within minutes, water clear | Sand | A relatively open filter catches it without restricting flow |
| Fine layer after hours, slight haze | Silt | Needs a finer rating, and will load the cartridge faster |
| Still cloudy, nothing settled | Colloidal clay or dissolved iron | Not sediment. A sediment filter will not fix this |
| Orange staining on the glass, no grains | Dissolved iron | Wrong product entirely — this needs treatment, not filtration |
If the jar is still cloudy after a day, stop and get the water tested. Buying a sediment filter at that point spends money and changes nothing, and the rows above are why.
What actually decides the choice?
Four things, in this order. Only one of them is the micron number everybody leads with.
1. Flow rate, in gallons per minute. A filter housing has a flow capacity, and exceeding it causes pressure loss whatever the cartridge. Size the housing to the whole-house peak flow, not to the average. This is where undersizing hurts most and it is the least discussed.
2. Micron rating, matched to the jar test. Finer is not better. Finer means more frequent changes and more restriction, for water that may already be clean enough.
3. Whether it is cleanable. A spin-down or reusable screen handles sand indefinitely and is flushed rather than replaced. A cartridge handles finer material and is consumable. On a well producing real sand, a cleanable pre-filter ahead of a cartridge outlasts either on its own.
4. Where it goes in the system. Before the pressure tank or after it, and ahead of or behind any booster or treatment equipment. This changes both what the filter protects and how the system behaves when the filter loads up.
Where should the filter go?
This matters more than most buying advice admits, because the position changes what happens when the cartridge blocks.
After the pressure tank is the usual place for a cartridge filter, and it has a real advantage: a blocking filter reduces pressure at the fixtures but does not make the pump work harder, because the pump is still filling the tank against the same pressure.
Before the pressure tank puts the restriction on the pump’s side. As the cartridge loads, the pump takes longer to reach cut-out and eventually may not reach it at all — which presents as a switch fault. This is a real failure mode and it is the argument against pre-tank cartridge filters.
A cleanable spin-down screen before the tank is the exception, and a good one. It catches coarse sand before it can get into the tank and the switch’s sensing nipple, and because it is flushed rather than loaded, it does not progressively restrict the pump.
Ahead of a booster or treatment equipment is where a filter earns its place protecting hardware, which is often the real reason to fit one.
Whichever you choose, check the tank’s precharge after any change to the system — air charge is the thing most often disturbed and most often blamed on something else.
What size housing and what rating?
The honest answer is that these two decisions are made against your own numbers, and there is no universal pair.
Housing: sized on peak simultaneous flow. A house where a shower, a washing machine and an outside tap can run together needs a housing rated above that combined flow, and a housing at its limit loses pressure before the cartridge is anywhere near loaded.
Rating: chosen from the jar test. Coarse for sand, finer for silt, and nothing at all for anything that did not settle.
A staged arrangement is usually the right answer on a dirty well — a cleanable screen for the coarse material, then a cartridge for the fine. Each stage then does what it is good at, and the cartridge lasts because it is not being asked to catch sand.
Products
Six filters, in the order the article argues for: the cleanable screen that catches sand, then the cartridge housing that catches what the screen cannot. Every figure below comes from the maker’s own published specification, and every one of the six returned a live listing on 5 November 2026.
Three things to read before the list. They are the reason some numbers here differ from the numbers on the retail page you will land on.
- Mesh is not microns, and the two do not agree even within one maker’s own documents. Rusco’s specification tables give 250 mesh as 50 microns. Retail listings for the same filter give 61 or 63 microns. We publish Rusco’s figure because it is the manufacturer’s, but no screen rating is a sharp cut-off, and a 20 per cent disagreement about where it sits is worth knowing.
- A “15 gpm” figure on a housing is usually not a maximum. Pentair’s Big Blue sheet gives flow figures as initial pressure drop at a test flow — 1 psi at 15 gpm. That is a different statement from “rated to 15 gpm”, and treating it as a ceiling will undersize the housing.
- A variant’s number is not the base model’s number. iSpring publishes a 20 gpm flow for the WSP-50SL. It does not publish one for the plain WSP-50, so you will not find one quoted here.
Stage one — the cleanable screen
#### Rusco 1-250-F, 1-inch spin-down
Here because it is the coarse stage, and because it never needs a replacement part. This is the answer to the first row of the symptom table — grit in the aerators and toilet tanks — and to nothing else on it.
| Flow capacity | 1–25 GPM |
| Max pressure | 150 PSI |
| Size | 11-3/8″ long × 5″ wide, 1″ slip port |
| Screen | polyester, 250 mesh (50 microns, per Rusco) |
| Cleanable or consumable | Cleanable — flush the valve, or pull the screen |
The clear bowl is the point. You can see the sediment arriving, which means you flush on evidence rather than on a calendar.
#### Rusco 1-100STSS-F, 1-inch Sediment Trapper, stainless screen
Here for one reason: it holds more before it needs flushing. Same flow and same pressure as the filter above, in a body three inches longer. On a well that loads a screen in days rather than weeks, that extra volume is the difference between a filter you maintain and a filter you resent.
| Flow capacity | 1–25 GPM |
| Max pressure | 150 PSI |
| Size | 14-3/8″ long × 5″ wide, 1″ slip port |
| Screen | stainless steel, 100 mesh (150 microns, per Rusco) |
| Cleanable or consumable | Cleanable, and stainless rather than polyester |
Note that it is coarser than the one above, not finer. Longer body, bigger holes — this is for sand in quantity, not for silt.
#### iSpring WSP-50
Here because there is no mesh number to get wrong. It ships at 50 microns and that is the only rating it has. For anyone who did the jar test, found sand, and does not want to choose between nine mesh options, that is a feature rather than a limitation.
| Screen | stainless steel mesh, 50 microns |
| Connections | 1″ MNPT + 3/4″ FNPT, lead-free brass |
| Operating range | 20–90 PSI, 40–100 °F |
| Cleanable or consumable | Cleanable — flushed out of the bottom |
| Flow | not published by iSpring for this model — see the note above |
#### iSpring WSP50ARJ, jumbo with auto-flush
Here for the failure that actually happens: nobody flushes it. A screen filter only works if someone opens the valve, and the row in the table about pressure dropping over days is very often a screen that was never flushed. This one flushes itself on a schedule.
| Flow | 25 GPM maximum |
| Capacity | 1 gallon |
| Screen | stainless mesh, 50 microns |
| Connections | 1″ MNPT + 3/4″ FNPT |
| Cleanable or consumable | Cleanable, flushed automatically |
It is the most expensive way to solve a problem that a two-minute habit also solves. Buy it if you know the habit will not happen — not because automatic is better.
Stage two — the cartridge housing
A cartridge is a consumable. It catches what the screen let through, it loads up, and it gets thrown away. Putting one in front of a well with sand in it, with no screen ahead of it, is how people end up changing cartridges every few weeks — the second row of the symptom table.
#### Pentair Pentek Big Blue, 10 inch, 1″ NPT (150238)
Here because it is the standard this whole category is measured against, and because 10″ × 4.5″ cartridges are the easiest filter element in the world to buy.
| Max pressure | 100 PSI (10″ housings) |
| Temperature | 40–100 °F |
| Size | 13.30″ × 7.45″ |
| Cartridge | takes 10″ × 4.5″ Big Blue cartridges |
| Flow reference | 1 psi initial drop at 15 gpm (1″ models) |
| Cleanable or consumable | Consumable — the housing is permanent, the cartridge is not |
No wrench and no mounting bracket in the box. The Big Blue bracket bolt pattern does not match standard 2.5″ housings, so an old bracket will not do.
#### Pentair Pentek Big Blue, 1-1/2″ NPT (150239)
Here for one reason, and it is the sizing argument above: a house where a shower, a washing machine and an outside tap run together needs ports that are not the restriction. Same body, same cartridge, wider openings.
| Max pressure | 100 PSI (10″ housings) |
| Cartridge | takes 10″ × 4.5″ Big Blue cartridges |
| Flow reference | 1 psi initial drop at 20 gpm (1-1/2″ models) |
| Cleanable or consumable | Consumable cartridge |
If you are already at your pressure limit, this is the version to buy. The cartridge does the same job either way; the ports decide what the housing costs you before the cartridge is even dirty.
What is deliberately not on this list
Culligan’s WH-HD200-C was on the research shortlist and came off it. Culligan publishes thorough documentation for its dealer-installed systems, but no specification sheet for that model could be retrieved — no flow rate, no micron rating, no pressure limit. A filter with no published rating cannot be compared with filters that have one, and this site does not publish a figure it could not fetch.
Nothing finer than 50 microns appears above. If the jar test produced cloudy water that never settled, every filter on this page is the wrong purchase — that is the sixth row of the symptom table, and it is a water treatment question, not a sediment question.
When does this need a pro?
- The jar is still cloudy after a day. That is a water test, not a filter purchase.
- There is staining but no grit. Dissolved iron and manganese need treatment chosen against a test result.
- The sediment started suddenly. A well that was clear for years and is not now has a cause — casing, seal, or water level — and a filter hides it.
- The pump is also short cycling or struggling to reach cut-out. Adding restriction to that system makes diagnosis harder.
- You are plumbing into the pressure side before the tank. Get the position decision right first; it has the failure mode described above.
FAQ
What micron rating do I need for well water sediment?
It depends on what is actually in the water, which a settling test tells you in a day. Sand that drops out within minutes is caught by a relatively open filter without restricting flow. Silt that takes hours to settle needs a finer rating and loads cartridges faster. Water that is still cloudy after a day is not carrying sediment a filter of this class removes.
Will a sediment filter remove iron from well water?
Not if the iron is dissolved, which is the common case. Dissolved iron passes straight through a sediment filter and only becomes visible as staining after it oxidises downstream. If the jar shows orange staining with no grains settling, the water needs treatment chosen against a test, not filtration.
Should the sediment filter go before or after the pressure tank?
After the tank is usually better for a cartridge filter, because a loading cartridge then reduces pressure at the fixtures without making the pump work harder to reach cut-out. A cleanable spin-down screen is the exception worth fitting before the tank, since it catches coarse sand before it reaches the tank and the pressure switch, and it is flushed rather than progressively blocked.
Why did my water pressure drop after fitting a sediment filter?
Either the housing is undersized for your peak flow, or the cartridge is finer than the sediment requires and has loaded quickly. Both reduce pressure while the filter is doing nothing wrong. Check the housing’s flow rating against the flow you actually draw, then reconsider the micron rating against a settling test.
How often should a well sediment filter be changed?
There is no interval that applies generally, because it depends entirely on how much sediment the well produces and how fine the cartridge is. The useful measure is pressure: a cartridge is due when pressure at the fixtures starts to fall. If that happens within days, the rating is too fine rather than the cartridge being faulty.
Do I need two filters for well water?
On a well producing real sand, a staged arrangement usually outlasts either stage alone — a cleanable screen for the coarse material, then a cartridge for the fine. The cartridge then lasts much longer because it is not being asked to catch sand it was never designed for.
