Sediment filters for well water

Best for

Wells that deliver grit, sand or cloudy water, and any home with UV, reverse osmosis, a chemical feed pump or a pH neutralizer downstream that needs protecting.

Wrong fit

Homes whose stains come from dissolved iron or manganese, which passes through a sediment filter. They need an iron filter instead.

Tradeoff

Finer filters catch more but clog faster and cut water pressure, so you trade clarity against how often you change cartridges.

What a sediment filter does (and doesn’t)

A sediment filter is a physical screen. It traps particles that are suspended in the water: sand, silt, clay, scale and rust flakes. Nebraska Extension says sediment filters reduce turbidity, the cloudiness caused by suspended solids.

It does not remove anything dissolved. That rules out:

• Dissolved iron and manganese. Water carrying them often looks clear coming out of the tap, then stains. An oxidizing whole house well water filter handles those.
• Bacteria and viruses. Use shock chlorination, UV or chlorination.
• Hardness, nitrate, arsenic and other dissolved chemicals.

If your problem is visible grit, a gritty feel in the toilet tank, or cloudy water that settles in a glass, a sediment filter is the right first step. More on sediment in well water.

What you’re seeing, and what to do

Not every particle problem is a sediment problem. Match the symptom first:

WQA notes that reddish and yellow-tan discoloration often comes from iron, while black or dark brown points to manganese. Those are dissolved metals that only become particles after they meet air, so a lab test for iron and manganese is worth doing before you buy any filter. See how to test well water.

Types of sediment filter

Nebraska Extension says cartridge media can be polypropylene, polyester, glass fiber, cellulose, ceramic or other materials, often wrapped or pleated to add surface area. It describes cartridge filters mainly as point-of-use devices and suggests talking to a water treatment professional about larger point-of-entry media filters.

Choosing a micron rating

A micron rating tells you the smallest particle the filter is designed to trap. Nebraska Extension gives the key details:

• A 10-micron filter traps particles 10 microns and larger.
• Many filters are rated only for 20 microns and larger, which may let some silt through.
• Nominal filters should trap about 85% of particles at their rated size.
• Absolute filters should trap about 99.9%.

The practical approach is to stage them, coarse to fine:

1. A spin-down screen or coarse cartridge to catch sand.
2. A finer cartridge after it if silt still gets through.

Going straight to a very fine cartridge on a sandy well means it clogs quickly and your pressure drops. Size each housing for your flow, too. Nebraska Extension suggests checking flow at household pressure, about 30 psi. A small housing on a big house will choke flow when several taps run.

Where it goes in the treatment order

Sediment filtration goes first in almost every well setup, because it protects everything after it:

• Chemical feed pumps. SpringWell’s chemical injection manual recommends a spin-down filter ahead of the system and warns that sediment can interfere with the flow switch. See chemical injection systems.
• pH neutralizers. Penn State notes neutralizers have to backwash out trapped particles unless a sediment filter is installed ahead of them. See pH neutralizers.
• UV systems. The Minnesota Department of Health says UV may need pre-filtration when turbidity is above 1 NTU, and Penn State says a sediment filter is often needed. See UV systems.
• Reverse osmosis. Connecticut DPH says a sediment pre-filter reduces membrane fouling. See reverse osmosis.

Nebraska Extension also notes sediment filters are used after aeration, ozonation or chlorination to catch the particles those processes create.

Choosing cartridge material

Cartridges look alike but behave differently. Nebraska Extension lists the common materials and a few points worth knowing:

• Pleated or wrapped media have more surface area, so they hold more before flow drops.
• Paper media can let bacteria accumulate, especially if a cartridge stays in service too long. Nebraska Extension suggests a nonbiodegradable material if that happens.
• Polypropylene, polyester and glass fiber are common nonbiodegradable choices.
• Gallon ratings on the package are only a rough guide, because sediment levels vary from well to well.

Buy cartridges sized for your housing (standard or larger “big” housings) and keep the same micron rating once you find one that works.

Install needs

• Shut-off valves on both sides, or a bypass, so you can change cartridges without draining the house.
• Clearance below the housing to unscrew the bowl and pull the cartridge.
• Pressure gauges before and after the housing make it easy to see when a cartridge is loading up.
• A drain or bucket access for spin-down flushing, and a floor drain for any backwashing media filter.
• Mounting. Cartridge housings are heavy when full. Use a bracket on a wall or stud rather than letting pipes carry the weight.

Maintenance

• Change cartridges when flow drops. Nebraska Extension says flow is highest with a new cartridge and gradually decreases as trapped material builds up. Gallon ratings are only a rough guide.
• Flush spin-down screens often enough that the collection cup never fills.
• Watch for bacteria. Nebraska Extension notes bacteria can accumulate on filters, especially paper media, and suggests regular replacement or a nonbiodegradable media.
• During shock chlorination, take filters out of their housings first. The Minnesota Department of Health includes this step in its well disinfection instructions, and the housing gets disinfected along with the plumbing.
• Keep spares on hand so you aren’t tempted to run a clogged cartridge for weeks.

When sediment is a well problem, not a filter problem

A filter treats the symptom. If sand appears suddenly, gets worse, or comes with air spurts or a pump that cycles oddly, have a licensed well contractor check the well and pump before you buy more filtration. Sand that shows up suddenly can point to a well or pump problem that no cartridge will keep up with.

Also test for coliform bacteria if cloudiness appears after heavy rain. Penn State says bacteria levels in wells tend to be highest after several weeks of wet weather, and cloudy water after storms can mean surface water is getting in.

Who should skip it

• Clear water with no grit, and no UV, RO or chemical feed downstream that needs protecting.
• Stains from dissolved iron or manganese. A sediment filter alone won’t stop them.
• Cloudiness from fine particles that pass every cartridge. WQA lists filtration among several options for cloudiness and suggests looking for products certified for particulate or turbidity reduction. A water treatment professional can help choose between a backwashing media filter and other approaches.

To see what else your lab report calls for, enter your numbers at /test-results/.