Water Testing
A water test tells you what to treat and how much of it there is, which is what sizes a system. Buy the equipment after the test.
Well water
Private wells aren’t covered by the federal drinking water rules, so testing is up to the owner. Use a state-certified lab; many county health departments run well tests or can name a lab. A test for treatment should cover:
- Total coliform bacteria and E. coli
- Hardness
- Iron and manganese
- pH and total dissolved solids (TDS)
- Hydrogen sulfide, if the water smells like rotten eggs
- Nitrate, arsenic and lead
Test once a year for bacteria and nitrate, and again after flooding, well work, or a change in taste, color or smell.
City water
Your utility publishes a Consumer Confidence Report each year with its test results. The two things to look for are hardness, and whether it disinfects with chlorine or chloramine. Chloramine needs catalytic carbon; standard carbon removes chlorine but little chloramine. Lead usually comes from a home’s own pipes and fixtures, so test at your tap if the house was built before 1986.
Reading the results
| Result | Reference level | Usual treatment |
|---|---|---|
| Hardness | Hard above 120 mg/L (7 grains per gallon) | Water softener |
| Iron | Stains above 0.3 mg/L | Iron filter (air injection or oxidizing media) |
| Manganese | Stains above 0.05 mg/L | Iron filter or softener, depending on the level |
| Hydrogen sulfide | Any smell | Air injection, or catalytic carbon at low levels |
| pH | Below 6.5 corrodes pipes | Acid neutralizer (calcite) |
| Sediment | Visible grit or cloudiness | Spin-down or sediment filter |
| Coliform bacteria | Any positive result | Shock-chlorinate the well and retest; UV for ongoing protection |
| Nitrate | Limit 10 mg/L as nitrogen | Reverse osmosis at the kitchen tap |
| Arsenic | Limit 0.010 mg/L | Reverse osmosis or arsenic media |
| Lead | Any detected | A filter certified to NSF/ANSI 53 or 58 for lead |
Iron, manganese, pH and hardness levels come from EPA’s secondary standards and the USGS hardness scale; nitrate and arsenic are EPA’s limits for public water. An E. coli positive means the water isn’t safe to drink until the well is treated and retested; call your county health department.
Order of treatment
When a well needs several kinds of treatment, the usual order from the pressure tank is sediment filter, iron and sulfur filter, softener, then UV last, so the UV lamp sees clear water. UV lamps need iron below 0.3 mg/L and hardness under about 7 grains per gallon to stay clean.
Sizing a softener
Multiply hardness in grains per gallon by the number of people and by 75 gallons a day. A softener that holds about a week of that, between regenerations, is the usual size.
Send your results to [email protected] with any question about matching a system to them.