Cleaner water starts with the right cartridge
A whole-house sediment filter is usually the first cartridge your water meets. It captures dirt, sand, rust, and other suspended particles before that water reaches your faucets, showers, appliances, and any other filters in your system. Choosing the right replacement comes down to three things: length, diameter, and micron rating.
Step 1 — Get the size right
Your filter is described as Length / Diameter / Micron — for example, 10" / 4.5" / 5.
- Length — 10" or 20": Measure your old cartridge from top to bottom, or check the height of your filter housing.
- Diameter — 2.5" or 4.5": Measure across the end of the cartridge. 2.5" cartridges fit standard slim housings. 4.5" cartridges fit wide housings, commonly called Big Blue style housings.
No old cartridge to measure? Measure the inside of the housing sump (the clear or blue cup that unscrews) — its height and width tell you which cartridge size it takes.
Step 2 — Pick your micron rating
The micron rating is how fine the filter is. Lower number = finer filtration. Finer is not automatically better: a very fine cartridge on dirty well water can clog quickly and reduce water pressure, so match the rating to your water.
- 100 micron — Coarsest. Heavy grit and large sediment, often as a first stage on well water.
- 50 micron — Coarse sediment, sand, and scale flakes.
- 30 micron — General sediment protection for homes with moderate dirt and rust.
- 20 micron — Everyday whole-house sediment control. A good starting point for many city-water homes.
- 10 micron — Finer dirt and rust, better protection for appliances and downstream filters.
- 5 micron — Fine sediment. Popular for well water with fine sand and silt.
- 1 micron — Finest in our range. Best where the water is already fairly clean, or as a later stage after a coarser cartridge.
The safest choice: match the size and micron printed on the cartridge you are replacing. It was chosen for your water and your housing.
Step 3 — Standard or antimicrobial?
Both are polypropylene string-wound sediment cartridges in the same sizes and micron ratings.
- Standard String-Wound — Dependable everyday sediment filtration, from $5.20.
- Antimicrobial String-Wound — The same sediment filtration, with antimicrobial protection designed to help inhibit microbial growth on the cartridge itself between changes, from $12.45. It is still a sediment filter — it does not disinfect water.
Well water or city water?
Well water usually carries more sand, silt, and rust, so most well homes start coarser (20–50 micron) or use a coarse cartridge first. City water is treated before it reaches you, so a finer cartridge (5–20 micron) typically lasts longer before it needs changing.
When should I change my cartridge?
Change it when you notice a drop in water pressure, when the cartridge is visibly loaded with sediment, or on your housing manufacturer's schedule. How long a cartridge lasts depends entirely on how much sediment is in your water — a well home in spring runoff will go through cartridges faster than a city home.
Still not sure? Contact us with your housing size and what is in your water, and we will point you to the right cartridge.
What micron do I need? A quick decision guide
Work from your water, not from a guess. Coarse sediment and heavy well-water grit — visible sand, particles you can feel — call for 50–100 micron as a first stage. General whole-house sediment for an average home is 20–30 micron. Finer dirt and rust, and the most popular all-round replacement choice, is 5–10 micron, with 5 micron the default buy. One micron is the finest rating in this line and belongs as a final polishing stage only: on silty well water a lone 1 micron cartridge can clog in days and cut your pressure. If two stages are an option, step down gradually — for example 50 micron, then 20 micron, then 5 micron — so each cartridge lasts longer. Full detail: What Micron Sediment Filter Do I Need?
How often to change your cartridge
Every 3 to 6 months for most homes. Change sooner when flow slows, pressure drops by about 10–20 PSI across the housing, or the cartridge is visibly loaded and discoloured. Well-water homes often change more often in spring and after heavy rain. See How Often to Change a Whole House Sediment Filter.
String-wound vs pleated vs melt-blown, in one line each
String-wound (what Hydrana makes) is a graded-depth cartridge with high dirt-holding for dirty water. Pleated is a surface filter with high flow that can sometimes be rinsed at coarser ratings. Melt-blown (spun) is a low-cost depth cartridge that is strong at fine ratings. The honest comparison is in String-Wound vs Pleated vs Melt-Blown Sediment Filters.