Iron, manganese and hard water by source

Published hardness figures are scarce here: Lakewood Water District gave 70 mg/L in 2016 and Lakehaven lists data well by well, so check your supplier's report, and get a lab test before treating a well.

Revised November 4, 2026

Why there is no one number for the South Sound

The source decides it, and sources vary from one supplier to the next. Tacoma Water draws mostly on the Green River and uses wells for part of its supply. Lakewood uses groundwater alone, from many wells. Puyallup has springs and wells, while Kitsap PUD's systems all run on wells. Where a supplier blends sources, the water can vary too. So a neighbor's result on another system tells you little, and knowing your supplier comes first.

Be careful with old or borrowed figures. We found hardness numbers on vendor and lookup sites that conflict widely, and we left them out. One table in Tacoma Water's 2025 report belongs to a City of Bonney Lake supply for a single subdivision, so it says nothing about the Tacoma system.

What each substance does

Hardness mainly affects soap and scale, iron and manganese mainly stain, and manganese carries a health note as well. The Department of Health says manganese occurs naturally, that too much can be harmful especially to infants, and that it can stain laundry. For a well with manganese showing, that makes a lab test a health question and not only a laundry one.

A rusty tap may have nothing to do with the source. Tacoma Water says older galvanized plumbing past the meter can release rust and grit at the tap. If only certain taps show it, or it comes and goes, read old lines and what they shed before buying any filter. On a supplier's system, report it to the supplier first.

Where the numbers come from

Your supplier's annual water quality report is the first place to look. It is the record the utility itself stands behind, and it carries a date. Lakehaven says its report is online at lakehavenwsd.gov/CCR from July 1, 2026. Where a report leaves hardness out, as Tacoma Water's seems to, ask the water quality office. Write the figure down with its date and the unit, since mg/L and ppm figures are what you will compare with a lab report.

If you are on a well, nobody else tests for you. The Department of Health makes private well owners responsible for their own testing. The health schedule on the private wells page comes first, because bacteria and nitrate matter more for safety than staining. Add iron, manganese and hardness to the order, and ask the lab how to collect the samples.

When treatment fits

Treatment fits after a lab report names what is in the water and how much. Before that, you could be paying to treat the wrong thing. A stain may come from pipes, a change may come from a repair, and a softener doesn't answer a bacteria result.

The Department of Health points to NSF International and UL as certifiers of home treatment units, so look for that listing and for the specific substance it covers. Then ask your permit office whether the install needs a permit, as set out in plumbing permits by place. Keep the lab report. A repeat test after installing is how you learn whether the unit is doing its job.

Pages for individual places, such as the Lakewood sheet and the South Hill sheet, list the supplier to ask.

Once a lab test shows iron in your well water and you have decided to treat it, one range to compare is iron filters for well water. The same team runs SoftPro and this site.

If the same lab test shows hardness you want to treat, one product to read about is a well water softener. Quality Water Treatment and this atlas are run by the same team.