City Water vs. Well Water: What’s the Difference?
They come from different places, carry different problems, and need different solutions. Here’s how to think about yours.
Before we get into the differences, the foundation: all water starts in the ground. Every drop you drink, whether it came from a city treatment plant or a well in your own yard, originated as groundwater. City water is, in a sense, well water that’s been treated with chemicals on its way to you.
City water: treated with chemicals
Municipal water is treated to kill bacteria and stop disease, usually with chlorine or chloramine. That treatment is doing important work. But the chemicals don’t disappear once they’ve done the job. They come right through your tap. Chlorine also reacts with naturally occurring organics in the water to form disinfection byproducts (DBPs) like trihalomethanes, which some studies link to long-term health concerns.
On top of that, city water travels miles of pipes to reach your home. Older pipes can pick up sediment, rust, or even traces of lead. The treatment plant doesn’t control that part.
Well water: yours alone
A private well taps directly into groundwater under your property. No one is testing it but you. What’s in the soil and the local watershed is what’s in your water.
Common well water issues:
- Hardness (calcium and magnesium) that scales pipes and dries skin
- Iron and manganese that stain sinks, laundry, and porcelain
- Sulfur (hydrogen sulfide) that smells like rotten eggs
- Bacterial contamination, especially after heavy rain or flooding
- Pesticide and herbicide runoff from nearby agriculture
How to choose a filter
The short answer: test first. The longer answer: a city home and a well home almost always need different setups. A catalytic carbon filter is great for chlorine, which makes it the right call for most city homes, but it’s seldom the answer for well water dealing with iron staining. A reverse-osmosis system handles dissolved solids at a .0005 micron removal rating, but you don’t need one if your TDS reading is already low.
The right system is the one your test result points to. Anything else is a guess.