· Michael Blair
Metro Water Services publishes an annual water quality report, and Nashville water meets regulatory standards. Meeting standards is not the same as having nothing in it, and the things present determine which treatment is worth buying.
Hardness
Middle Tennessee sits on limestone, so the water is moderately hard — calcium and magnesium dissolved from the rock. It is not a health matter and it is the reason for scale on fixtures, cloudy shower glass and shortened water heater life.
Only a softener addresses hardness. Filters do not.
Chlorine and by-products
Disinfection is necessary and leaves residual chlorine or chloramine, which is what people taste. Disinfection by-products form when it reacts with organic matter.
Carbon filtration removes chlorine taste effectively and is the cheapest meaningful improvement most households can make.
- Hardness: only a softener addresses it
- Chlorine taste: carbon filtration
- Lead: from household plumbing, not the source
- Sediment: whole-house sediment filter
- Read the annual water quality report for your area
Lead
Lead is not present at the treatment plant; where it appears it comes from service lines and household plumbing, particularly pre-1986 solder.
That makes it a house-specific question rather than a city-wide one, and it is answered by testing your own tap rather than by reading the utility report.
Start with a test
A test of your own tap tells you what you actually have, including anything contributed by your own plumbing. The utility report describes what leaves the plant.
It is inexpensive and it stops you buying treatment for a problem you do not have, which is the most common outcome of buying from a sales visit.