Sediment Filter Replacement: How Often and How to Do It
A whole-house sediment filter protects your water heater, appliances, and faucet aerators from particulates in your water supply. Most homeowners either replace them too rarely (risking clogs and pressure drops) or haven't thought about it at all. Here's what you need to know.
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Do you even have a sediment filter?
Not all homes do. Look for a canister-style filter housing (usually a white or clear cylindrical unit, 10 inches tall) on the main water supply line where it enters the house — typically near the water meter, in the basement, or in a utility room. It's usually installed before the water heater and any other whole-house treatment.
If you have well water, you almost certainly have (or should have) a sediment filter — well water carries significantly more particulates than municipal water. If you're on city water, a sediment filter is optional but useful in areas with aging pipe infrastructure.
How often to replace
Replacement frequency depends entirely on your water quality — not calendar time. The right answer is "when the filter is visibly dirty or when pressure drops."
- City water, average quality: Every 3–6 months.
- City water with visible sediment or rust: Monthly or as needed.
- Well water, clear: Every 1–3 months.
- Well water with visible turbidity or iron: Monthly or more, depending on severity. Consider a separate iron filter upstream.
The practical test: buy a clear housing or check the color of the cartridge when you replace it. If it's brown or heavily discolored, replace more often. If it's barely colored, you can extend the interval.
Choosing the right micron rating
1–5 micron
Fine filtration — removes fine silt, sand, rust, and most sediment. Higher flow restriction, clogs faster. Use as a final stage filter or when water quality is very poor. A 5-micron filter is the most common choice for whole-house primary filtration.
10–20 micron
Coarser filtration — removes larger particles (sand, gravel-scale sediment) while maintaining better flow. Often used as a pre-filter before a finer stage. Good choice for wells with sandy water where you need high flow without constant clogging.
50–100 micron
Very coarse — catches only large debris. Rarely used for primary household filtration. Useful as a pre-filter in irrigation systems or before a fine cartridge filter to extend its life.
Sediment vs carbon block
Sediment cartridges (spun polypropylene) handle particulates only. Carbon block cartridges also reduce chlorine, VOCs, and some contaminants but cost more and have shorter lifespans. For a whole-house primary filter, sediment cartridges are the correct and cost-effective choice.
How to replace the cartridge
- Step 1: Shut off the water supply to the filter (the shutoff valve upstream of the housing). Open a faucet downstream to relieve pressure.
- Step 2: Use a filter housing wrench (usually included with the housing, or $10 separately) to unscrew the housing sump counterclockwise. Have a towel ready — residual water will drain out.
- Step 3: Pull out the old cartridge. Note its condition — this tells you a lot about your water quality and whether you're replacing at the right frequency.
- Step 4: Rinse the housing with clean water. Check the O-ring in the housing cap — if it's cracked or deformed, replace it (O-rings typically come with replacement cartridges).
- Step 5: Insert the new cartridge, thread the housing back on hand-tight, then use the wrench for one additional quarter-turn. Don't overtighten — you'll crack the housing.
- Step 6: Restore water slowly and check for leaks at the housing threads. A small seep that stops after pressure stabilizes is normal; ongoing leaking means the O-ring isn't seated or the housing is cross-threaded.
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