Photo: Muselsom, “Water preparing bottles”, CC BY-SA 4.0, via Wikimedia Commons. Resized and converted to WebP; shown cropped.
Water treatment: the basics
Softeners, filters, reverse osmosis, UV, iron and sulfur systems, water testing.
The full guide for this trade is being written. Until then, here is what we know for sure: the problems that belong here, who handles them, and how to check a contractor.
On this page4 sections: urgent, permits…
What people call about
- Water tastes bad
- Hard water spots
- Sulfur smell in the water
- Whole-house filter
How soon to call
Call in the next day or two
Brown water from every tap
Ask for: iron treatment (on city water, ask the utility first; flushing hydrants causes it)
UV light for the well water
Ask for: UV disinfection
Schedule it
Plumb in a water softener
Ask for: softener installation
Water tastes bad
Ask for: water testing and filtration
Sulfur smell in the water
Ask for: sulfur treatment (and water heater anode check)
Hard water
Ask for: water softener
Water softener not working
Ask for: softener repair
Cloudy water
Ask for: sediment filtration
Test my well water
Ask for: certified lab water test
Reverse osmosis under the sink
Ask for: reverse osmosis installation
Whole-house filter
Ask for: whole-house filtration
Test the water for lead
Ask for: lead testing and point-of-use filtration
PFAS in the water
Ask for: PFAS treatment
Blue green stains in the sink
Ask for: acid neutralizer
General guidance, not a diagnosis. If anyone is in danger, call 911 first.
Permits and licensing
- Some of this work needs a permit, depending on the job and the town. Ask before the work starts.
- Licensing depends on the state: a trade license in some, a home-improvement registration in others, none in the rest. The finder shows what the record says where one exists.
Know what you're looking at
Softeners use salt, which you refill. Ask how often, how much it uses and where the wastewater goes, since some places limit softener discharge.
Whole-house filters and softeners are tanks with a control valve. Ask about the filter media, how often it is replaced and what the system does with its flush water.
General information, not legal, tax, engineering or insurance advice. Rules and prices vary by place, so get three local quotes. Problem list updated 2026-10-04.