Well Water vs City Water: What's Different & Why It Matters

Well water comes up from the ground under your own property, and nobody treats it or tests it except you. City water comes from a river, a lake, a reservoir or a city well, and a utility treats and tests it under federal rules before it reaches your faucet. The first thing I ask a caller is "Are you on city water or well water?", because the answer changes everything I tell them next. One thing surprises people: in the lab tests my customers send in, hard water turns up just as often on city water as on a well.

Well water vs city water side by side

The core difference is who is responsible: with a well it is you, and with city water it is the utility. Everything else on this table follows from that.

Where your tap water comes from

Tap water comes from one of two places: surface water (rivers, lakes and reservoirs) or groundwater (the water held in the sand and rock underground, called an aquifer). In 2015, 61 percent of the water public utilities drew came from surface water, according to the USGS, while households that supply their own water, typically from a well, drew 98 percent of it from groundwater. The diagram at the top of this page shows both paths.

The path from the plant to your tap

A utility pipes the water from its source to a treatment plant. The CDC lists the usual steps:

1. Coagulation. Chemicals are added that make dirt and fine particles stick together.
2. Flocculation. Gentle mixing turns those particles into larger, heavier clumps.
3. Sedimentation. The clumps settle to the bottom.
4. Filtration. The clear water on top runs through filters of sand, gravel or charcoal.
5. Disinfection. Chlorine, chloramine or chlorine dioxide kills the germs that are left.

Plants commonly adjust the pH next, which cuts down corrosion in the pipes, and add fluoride. The plant leaves a small amount of disinfectant in the water on purpose, so it keeps killing germs in the pipes between the plant and your house. From there the water runs through the mains under the street and through your meter into the house. River and lake water usually needs more treatment than groundwater, because it carries more sediment, germs and chemicals.

A community well counts as city water

Some neighborhoods get their water from a few shared wells instead of a big river plant. I live on one: it's treated like city water, with chlorine and a product to raise the pH. Under federal rules, any system that serves at least 15 connections or 25 people for 60 days a year is a public water system, whether a town or a private company owns it. So a community well is tested under the same federal rules as city water, and the city water sections of this page are the ones for you.

Are you on city water or well water?

The quickest way to tell is your water bill.

• You get a water bill from a utility. You are on city water, or on a community well that counts as city water. The utility's name is on the bill.
• No water bill, and a pressure tank where the water line comes into the house. You are on a private well.
• Still not sure? Your deed or home inspection report says which, or call the local water utility with your address.

What the lab tests found in each

Hard water is just as common on city water as on a well: about 4 in 10 of both kinds of test came back hard. Hard here means 7 grains per gallon or more. The rest of the list splits the way you would expect. Iron, manganese and low pH are well problems: the city tests rarely showed them and never showed iron. These are the certified lab tests my customers have sent in since May: 407 from wells and 50 from city water.

The iron and manganese lines are the EPA's guidelines for staining, and 15 ppb is the EPA's action level for lead. Put together, 8 in 10 of the well tests showed at least one of hard water, bacteria, iron, manganese or acidic water. Lead usually comes from the plumbing, not the ground: the EPA says it gets into water when pipes, faucets or fixtures that contain lead corrode, especially when the water is acidic. If you already have a report, how to read your well water test results walks through it line by line.

Have a lab report or a utility report?

Text me a photo of your report

Well or city, send me the page with the numbers and I'll tell you what matters on it and what, if anything, you need.

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

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

What well water needs

A well needs a full lab test first, because the test at a home sale only checks bacteria, nitrates and cloudiness. It tells you the water is safe to drink that day, not whether you have low pH, iron, hard water or a sulfur smell. The EPA says to test a private well every year for coliform bacteria, nitrates, total dissolved solids and pH; before you move in, I would also test hardness, iron, manganese and sulfur.

Then the test decides what goes in: an iron filter for iron and manganese, an acid neutralizer for low pH, a softener for hard water. In my view every house on a well should have a UV light for bacteria; any time I've lived on a well I put one in, whether the test showed bacteria or not. For a house you are getting ready to move into, I would budget about $2,500 to $3,500, depending on what the test finds, and it may only cost $1,000. The guide to what a well water system costs breaks that down by problem, and the order well water treatment goes in matters once you have more than one tank.

On a well with no lab test yet

One lab test shows what your well needs

One certified lab test, mailed to you, run by an accredited lab, reports bacteria, pH, iron, manganese and hardness from one kit. If you already have a lab report, skip this.

Get the certified well water test

$199 for 53 contaminants. On city water, the city water test is linked below.

What city water needs

On city water I recommend two tanks: a carbon filter first for the chlorine, then a softener for the hardness. The carbon goes first because chlorine shortens the life of the softener resin. It is what I run in my own house. My community well water is treated with chlorine, and straight from the line it tastes bad. I tried a salt-free system first and it didn't do anything; with a salt-based softener and the carbon filter in, the water is perfect through the entire house. I use one 40 pound bag of salt every 30 to 45 days, and the carbon lasts 5 or 6 years before it needs replacing. One honest caveat from the CDC: once a whole-house filter takes the chlorine out, more germs may grow in the house plumbing.

Before you buy anything, get your utility's water quality report. Every community water system has to send one each year by July 1, and the utility's name is on your water bill. I tell callers to call the utility and ask for the report on what they find in the water: they have to give it to you, and it's free. You can also look up your water system's federal record by ZIP code.

What the report cannot show is your own plumbing. Everybody on the same city system gets the same water from the plant, but copper pipe with lead solder joints or old brass fixtures can add lead on the way to your faucet. The EPA says lead pipes are more likely in homes built before 1986. That is when a test at your own tap earns its keep: the city water test kit ($199, a certified lab, 47 contaminants) reports lead, copper, hardness and pH from your faucet.

The two-tank package with a 1.5 cubic foot carbon filter and a 48,000 grain Fleck 5600SXT softener is $3,195. Like everything we sell, it ships to your door with the media in separate bags. I recommend a plumber who has installed water treatment before; I'm a phone call away for your plumber at 800-460-5810, and if you'd rather do it yourself, text me at 443-277-2204 with any questions. For more on each piece, see whether you need a softener on city water, running a carbon filter and softener together and whether chlorine in water is bad for you.

Is well water healthier than city water?

Neither source is healthier by default; it depends on what is in your water and whether you treat it for that. City water has a safety system built in: the EPA says over 92 percent of people on community water systems get water that meets every health-based standard all of the time. Well water has no chlorine and no added fluoride, but it also has no one checking it.

The real risk with well water

The biggest risk with well water is not testing it. Without regular testing, you could be drinking water with unsafe levels of bacteria, nitrates, arsenic, or other contaminants that have no taste, smell, or color. In the tests my customers send in, 13 of the 407 wells had arsenic over the EPA's limit of 10 parts per billion. A tested, treated well can be excellent water; an untested one is a guess. If you are on a well and have not tested in the past year, that is the next step, and whether your well water is safe to drink covers what to test for.

Moving from city water to a well

If you just moved into a house on a well and you have never been on one, the biggest change is that the water is now yours to test and treat. The test the settlement company ran checks for nitrates, bacteria and turbidity (cloudiness) to make sure the water is safe to drink. It does not look for low pH, iron, hard water or a sulfur smell, and those are what you live with every day.

The first few days tell you a lot. Reddish-brown stains in the toilet mean iron. Blue-green stains in the tub and shower you use most mean acidic water. A rotten egg smell means sulfur, and a metallic taste can be iron or copper from pipes the acidic water is dissolving. If the last owner left tanks in the basement and you do not know what they do, have the water tested before the system and after it. You also have a well pump and a pressure tank now instead of a water main; if the pressure swings bother you, a constant pressure well system evens them out. The step-by-step guide for new well owners covers the rest in order.

Moving from a well to city water

This move is simpler. You will notice the chlorine: that taste is the disinfectant the plant leaves in the water on purpose, and a carbon filter takes it out. Hardness may come with you, since about 4 in 10 of the city tests were hard, so a softener can still earn its place. The iron filter, acid neutralizer and UV light from a well usually have nothing to do on treated city water. And if the house is older, check the plumbing for lead, as covered in what city water needs.

Frequently asked questions