Guide
City water and well water are different problems
One is monitored, regulated, and reported. The other is entirely your responsibility. That changes where treatment starts.
Who is watching the water
A public water system is sampled on a fixed schedule, reports to a state regulator, must meet federal limits, and publishes an annual Consumer Confidence Report describing what it found. If something goes wrong you are notified, sometimes within 24 hours.
A private well has none of that. No agency samples it, no report is produced, and nobody will contact you if the water changes. The owner is the entire quality assurance system.
That single difference reshapes everything. On city water you are mostly filling gaps in a system that already works. On a well you are starting from nothing.
On city water, the pipes are the open question
The utility is responsible for water quality up to the property line. What happens in your own service line and internal plumbing is yours, and that is where lead enters if it enters at all.
So the useful questions on a public supply are narrow. Does the municipal service line inventory list your address as lead or unknown. Was the building plumbed before 1986, when lead solder was restricted. Does the taste or smell bother you. Is the reported hardness high enough to be shortening appliance life.
Most households on a well-run public supply need either nothing or one point-of-use filter. That is a genuinely common outcome and we will tell you when it applies.
On a well, everything starts with a laboratory test
The minimum annual panel is total coliform and E. coli, nitrate, and pH, with hardness, iron, and manganese included because they shape equipment selection. Arsenic, radon, and PFAS are added where local geology or land use makes them plausible.
Test annually, and additionally after flooding near the well head, after any work on the well, and if anything changes in how the water looks, tastes, or smells. Test immediately if there is a pregnancy or an infant in the household, because the nitrate limit exists specifically for that risk.
Wells change. Rainfall, nearby land use, and the age of the casing all shift what is in the water, so a treatment train matched to a five year old test is matched to water that may no longer exist.
Why well treatment is staged
There is no standard well water system, because two wells a mile apart can need completely different equipment. What there is, is a standard order, because each stage protects the next.
Sediment removal first, since particles foul everything downstream. Oxidation and iron filtration next, because iron coats a quartz sleeve and fouls softener resin. pH correction before softening, since a calcite neutraliser raises hardness as it works. Softening before any point-of-use reverse osmosis, which extends membrane life. Ultraviolet disinfection last, closest to the house.
Get that order wrong and equipment fails early while appearing to run normally.
Some well problems are not treatment problems
A positive bacteria result often means a physical pathway exists between the surface and the water. A failed well cap, a cracked casing, a wellhead below grade that floods, or a septic system too close.
In those cases the repair comes first, then shock chlorination, then a retest. Fitting a UV lamp over an unrepaired intrusion treats the symptom and hides the fault, and it leaves the household relying entirely on a lamp that needs annual replacement and stops in a power cut.
Well construction and pump work is a separately licensed trade in every state we cover. We install treatment downstream of the pressure tank and refer the rest.
Common questions
My well water has always been fine. Do I still need to test?
Yes, annually. Almost nothing that matters in well water can be seen, tasted, or smelled. Nitrate, arsenic, and PFAS are all invisible, and bacteria frequently are too. Water that has always seemed fine is exactly the water most likely to go untested, which is why the recommendation is a schedule rather than a reaction.
Is well water healthier than city water because it has no chemicals?
No. Well water has no disinfectant residual, which is a genuine reason it sometimes tastes better, and also the reason it has no protection against bacteria entering the system. Public supplies are treated and monitored precisely because untreated groundwater is not automatically safe. Both can be good water. Only one of them is being checked by somebody else.
I am moving from city water to a well. What changes?
Get a full laboratory panel before you rely on the supply, and do not assume the seller's test is current or complete. Budget for annual testing as ongoing maintenance. Expect that equipment sized for your old address may be unnecessary at the new one, and have it reassessed rather than reinstalled by default.
Related reading
- water filters: well water
- water problems: bacteria in well water
- guides: how to read your water quality report
Other guides
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