How to Choose a Sediment Filter for Your Well (Decision Guide)

Most people who call me about a sediment filter for a well end up with the same thing: the 20 inch Big Blue with a 5 micron cartridge, mounted on the wall right after the well tank. If only 1 or 2 people live in the house, the 10 inch does the job. If you are changing a cartridge every week, no cartridge is going to fix that, and the answer is the backwashing tank. The Rusco spin-down is a coarse screen, and it goes last in line to catch media the tanks let past. Below is how I get to that answer with a caller: what you see in a glass of your water, how many people and bathrooms, and what the filter has to protect.

Look at your water in a glass

Fill a clear glass at the kitchen tap and watch it for a minute. If the specks rise and disappear, that is air; if they settle to the bottom or the water stays cloudy, that is sediment. It is the question I asked a man in Florida this month who had "dust particles floating around" in a glass from a system another company had just installed: some of his disappeared, which is air, and some settled, which is sediment. If the particles are really small, a 5 micron cartridge filter is what pulls them out.

Color matters too. A man with a cottage called in July about "a brownish orange color" in his toilets: that one is iron, not sediment, and a cartridge will not touch it. The table above sorts the three by what you are looking at.

Which size for your house

If 1 or 2 people live in the house, the 10 inch Big Blue is enough; anything bigger than that gets the 20 inch. Both housings take the same 4.5 inch cartridge and both are rated by Pentek at a 1 psi pressure drop at 15 gallons a minute, so the 20 inch is not about pressure on day one. That 1 psi is the empty housing; the cartridge adds its own drop, and the drop grows as the cartridge loads. The 20 inch holds twice the cartridge, so it goes longer between changes and keeps its flow longer as it loads up. Most homes buy one of the first two rows below and stop there. The two Rusco rows are the add-on screen at the end of the line, and the last row is for wells where a cartridge cannot keep up.

When a caller asks me 10 or 20, I tell them what I told a man in February who had no visible sediment and wanted a filter ahead of a neutralizer, softener and UV: "It's either the ten or the twenty. It doesn't really matter to me. The twenty-inch gives you better flow rates, and it has a longer period of time before you have to change the filter." A 3 bathroom, 4 bedroom house in May already had a 10 inch and asked whether to upgrade before adding UV. They water 5 acres off that well, so yes: the 20 inch gives better flow and you will not change it as often, and you want the small particles out before they reach the UV lamp.

Pipe size is not your flow number. The Rusco catalog says to pick the filter by flow rate, not by the pipe, and I see it on the phone: a man with about 8 bathrooms and 3/4 inch plumbing called last week worried about flow, and the answer was that everything on our systems is 1 inch and we do not see a drop in flow from the filter itself. The Big Blue kits and the Standard Rusco have 1 inch ports; only the Large Rusco is 2 inch. Your pump matters more than your pipe when a backwashing tank is on the table: the tank cleans itself with the pump's water, and a 13 inch tank wants about 14 to 18 gallons a minute to do it. Those are two different numbers: what the pump can push (the backwash uses that) and what the well makes over an hour (the well yield). A man last week had a pump rated 10 to 15 gallons a minute on a well that only makes 4 gallons a minute before it needs an hour to refill; the pump number is plenty for a backwash, and the yield is the number I want to talk through before anyone buys a tank.

If you do not know your gallons a minute, look at the well driller's report or the tag on the pump first. If you have neither, time a 5 gallon bucket at the spigot closest to the well tank with nothing else running: 30 seconds to fill is 10 gallons a minute, 20 seconds is 15. Send me that number with your bathroom count and the sizing takes a minute.

Which cartridge goes in the housing

Both kits ship with a 5 micron spun polypropylene cartridge, the plain white one; you throw it away when it loads, and the 20 inch replacement we sell is 5 micron as well. People ask me, "Can I just wash it off and reuse it?" and I tell them you can do whatever you want to, but we recommend replacing the cartridge when it becomes dirty. The 10 inch replacement we sell is Pentek's string-wound version, a polypropylene cord wound around a core, also 5 micron, and Pentek rates it at under 3 psi of drop at 20 gallons a minute. Any 4.5 inch cartridge fits the housing, so a pleated cartridge or Pentek's dual-gradient spun cartridge (dense outside, fine inside, which Pentek rates at up to 3 times the dirt-holding capacity of a plain cartridge) can go in if your water loads a plain one fast. Whatever the construction, stay at 5 micron.

Plan on a cartridge change every 4 to 6 months or so. It depends on how much sediment you have: it could be every 12 months, it could be every other month. The cue is flow dropping at the fixtures: when the shower weakens, the cartridge is loaded. The Big Blue housing is solid blue, so you go by flow and the calendar; only the Rusco has a clear bowl you can look at. The replacement cartridge is $45 for the 10 inch and $55 for the 20 inch.

Have your bathroom count ready?

Text me for the size

Send how many people and bathrooms, a photo of the glass or the toilet tank, and what equipment you already have. I will tell you 10 inch, 20 inch, or the tank, or that you do not need one.

Text Aidan443-277-2204 Call800-460-5810Aidan

8 AM to 5 PM Eastern, seven days a week. A real person, not a call center.

Where to put the filter

The Big Blue mounts to the wall right after your well tank and before your first water treatment system; the Rusco screen goes last, after the tanks. Never ahead of the well tank: Boshart, the fittings maker, says a filter between the pump and the tank hides a clogging filter from the pressure switch, so the pump runs against it. Every filter comes after the tank.

The reason the cartridge goes ahead of the treatment tanks is what sediment does inside one. If you skip the sediment filter and put in, say, an acid neutralizer, and you have a fair amount of sediment in the water, it gets into the neutralizer and works its way to the bottom, and when you add more calcite it compresses that sediment and slows your water flow or shuts it down. One cartridge housing ahead of the tanks is what I recommend. A second 5 micron housing in a row mostly adds a second pressure drop and a second cartridge to buy; if the first one is plugging fast, the answer is the longer housing or the tank, not a second cartridge. The Rusco is not a fine filter either way: its 60 mesh screen passes anything under about 250 microns, which is why it sits at the end of the line to catch the big pieces (media beads) that would plug a cartridge, and the 5 micron cartridge ahead of the tanks does the fine work. If the steps are the part you want, they are on install steps for a Big Blue or a Rusco, and the longer explanation of how a sediment filter works is on the complete guide.

When a cartridge is not enough

If sediment is clogging the inlets to your faucets and washing machine, or you are changing a cartridge on a weekly basis, you need the backwashing sediment tank. That is for grit or cloud in the glass; orange color is iron and a different tank. If you have no filter yet and do not know how heavy your load is, start with the 20 inch Big Blue: it is $195, and the first month tells you whether you need the tank. Any filter you put in, the smaller ones are going to clog quicker, so going down to a 10 inch never helps here. A man in June called with a cartridge that gets built up and, in his words, "within three months, it's completely clogged." That is iron and clay in the water, and with the 20 inch Big Blue people get about 6 months out of a cartridge on water like that. Three months is a cartridge problem you fix with the 20 inch; a week is a tank problem.

The tank is the same kind of unit as an acid neutralizer, a 13 by 54 inch tank with a Fleck 2510SXT valve on top, but with 2 cubic feet of Turbidex inside instead of calcite. Turbidex is a natural mineral media that takes suspended solids down to 5 microns or less, and instead of a cartridge you throw away, the valve runs water backward through the bed on a schedule and sends the dirt down the drain. It needs three things a cartridge housing does not: a drain within reach of the valve (1/2 inch line minimum), an electrical outlet for the valve, and a pump that can push about 14 to 18 gallons a minute through a 13 inch tank to clean it (that number is worked from the Turbidex media sheet, not measured on a well). Sediment heavy enough to clog the inlets to your faucets and washing machine is the case it was built for.

What ships: the tank, the valve with the bypass, and the Turbidex in bags with a fill funnel. The media is loaded into the tank at install; a loaded 13 by 54 tank weighs over 250 pounds and would be damaged in freight. No drain tubing is included with any filter on this page. I recommend a licensed plumber for the tank, and I support your plumber by phone at 800-460-5810.

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