Dirty well water is a description of a symptom, not a diagnosis, and the several things it can mean need entirely different treatment. A glass of water and half an hour of observation will narrow it down further than any product page, and doing that first is what prevents the common outcome of a filter that made no difference.
The standing glass test
Fill a clear glass and leave it on a windowsill. If sediment settles to the bottom, you have suspended particles: sand, silt or oxidized iron, and a mechanical filter is the right family of answer. If the water clears from the top downwards, it was carrying air or dissolved gas, which is a pressure tank or plumbing matter rather than a contamination one. If it stays uniformly colored for hours, whatever is causing it is dissolved, which means iron, manganese or tannins.
Gritty and sandy
Grit means the well is producing solids, and that deserves investigation before filtration. A failed or wrongly sized screen, a pump set too close to the bottom of the borehole, over pumping beyond what the aquifer sustains, or a collapsing formation all produce sand, and all of them damage the pump while a filter quietly handles the output. Have the well assessed, then fit a centrifugal separator or a backwashing sediment tank for what remains, first in the train ahead of everything else.
Colored, and which color
Orange to red staining that appears after the water stands is dissolved iron oxidizing in contact with air, treated by oxidation followed by filtration. Black specks and staining are usually manganese, treated similarly but less readily. Yellow to tea brown that stays uniform and stains fabric without leaving a deposit is tannins from decaying vegetation, which needs an anion exchange resin rather than any filter. Milky white that clears from the top down is air, which is not a water quality problem at all.
Test before you design
The EPA notes that private wells are not federally regulated under the Safe Drinking Water Act, that around 15 percent of the US population, over 43 million people in more than 23 million households, rely on them, and that a USGS study of 2,100 private wells found about one in five carried at least one contaminant above a human health benchmark. Visible dirt is a prompt to test for what is not visible: coliform, nitrate, pH, iron and hardness at minimum. Our well water filtration guide covers building the train from the result.
Questions people ask about dirty well water
How do I tell what is making my well water dirty?
Let a glass stand. Settling means particles, clearing from the top means air, and staying uniformly colored means something dissolved.
My well makes sand, should I just filter it?
Investigate first. A failed screen, a pump set too low or over pumping all produce sand and all damage the pump while a filter hides it.
The water is yellow brown and stains laundry, what is it?
Most likely tannins from decaying vegetation, which need an anion exchange resin. Iron reads more orange and leaves a rusty deposit.
What should I test for?
Coliform bacteria, nitrate, pH, iron and hardness at minimum. Visible dirt is a prompt to look for what is not visible.