Water, explained
Water, explained.
Plain-language notes on what is in household water and what each kind of treatment does. This is general information. It is not a substitute for a test of your own water.
Hardness
Hardness is dissolved rock.
Hard water carries calcium and magnesium picked up from limestone and other minerals. It is not considered a health concern, but it leaves scale on fixtures, spots on glass and shower doors, and deposits inside water heaters and valves.
Reports list hardness in milligrams per liter (mg/L, the same as parts per million) as calcium carbonate, or in grains per gallon (gpg), the unit most softeners use. One grain per gallon is about 17.1 mg/L.
5.8gpg
Moderately hard
About 100 mg/L as calcium carbonate
Drag the slider or use the arrow keys. Ranges follow the U.S. Geological Survey’s general classification, in mg/L.
Disinfection
Chlorine or chloramine?
Public water systems disinfect with one or the other, and some switch temporarily for maintenance. Your utility’s annual water quality report, the Consumer Confidence Report, says which one it uses.
Chlorine
- What it is
- Free chlorine, added so water stays safe on its way to you.
- How you notice it
- A pool-like smell or taste that fades if water sits uncovered.
- What reduces it
- Standard activated carbon handles it well, whole-home or at the tap.
Chloramine
- What it is
- Chlorine combined with a small amount of ammonia, so it lasts longer in the pipes.
- How you notice it
- Milder smell than chlorine, and it does not fade quickly when water sits.
- What reduces it
- Catalytic carbon with longer contact time. Standard carbon is far less effective. It also has to be removed before water goes into an aquarium.
Sediment
Sediment is what you can see.
Sand, silt, rust and scale flakes are more common on wells, after water main work and in older galvanized plumbing. Sediment filters are rated in microns: the smaller the number, the finer the particles they catch, and the sooner they clog. Staging coarse to fine keeps the finer filter working longer.
Coarse, around 50 micron
Sand and grit. A common first stage on wells.
Medium, around 20 micron
General whole-home prefiltration.
Fine, around 5 micron
Fine silt. A common prefilter ahead of carbon and reverse osmosis.
Reading a test
How to read a water test.
Start with the units, then compare each result to a reference point. The EPA’s secondary standards cover taste, odor, staining and scale; they are guidelines, not health limits. Review health-related results, such as lead, nitrate or bacteria, with the lab or your local health department.
Hardnessmg/L or grains per gallon
Reference point
No federal limit. Above 120 mg/L (about 7 gpg) is generally considered hard.
What it can mean
Scale on fixtures and glass, spots on shower doors, deposits in water heaters.
Treatment to ask about
Softening or salt-free conditioning.
Total dissolved solids (TDS)mg/L
Reference point
EPA secondary standard: 500 mg/L.
What it can mean
A broad measure of everything dissolved. High TDS often shows up as a salty, bitter or flat taste.
Treatment to ask about
Reverse osmosis at the drinking tap.
pH0 to 14, no unit
Reference point
EPA secondary range: 6.5 to 8.5.
What it can mean
Low pH water can corrode copper and leave blue-green stains. High pH can taste bitter and add to scale.
Treatment to ask about
Usually a well-water question; acid neutralizers raise low pH.
Iron and manganesemg/L
Reference point
EPA secondary standards: iron 0.3 mg/L, manganese 0.05 mg/L.
What it can mean
Orange-brown (iron) or black (manganese) staining in sinks, tubs and laundry; a metallic taste.
Treatment to ask about
Dedicated iron and manganese filtration, most often on wells.
Chlorine or chloraminemg/L
Reference point
EPA maximum residual disinfectant level: 4.0 mg/L.
What it can mean
Disinfectant from your utility. Present on purpose; mainly a taste and odor matter at the tap.
Treatment to ask about
Activated carbon for chlorine; catalytic carbon for chloramine.
Nitratemg/L as nitrogen
Reference point
EPA maximum contaminant level: 10 mg/L.
What it can mean
Mostly a private-well concern, especially near agriculture. Review any result with the lab.
Treatment to ask about
Reverse osmosis certified for nitrate reduction, at the drinking tap.
Lead and coppermicrograms per liter (ppb) or mg/L
Reference point
Utilities must act when household samples exceed federal action levels. Any lead result is worth discussing with the lab.
What it can mean
Usually comes from plumbing inside the building, such as older solder, fittings or service lines, not from the source water.
Treatment to ask about
A filter certified for lead at the tap, and a plan to replace lead-bearing plumbing.
Reverse osmosis
When RO makes sense.
Reverse osmosis is the most thorough treatment most homes will consider, and the most specific. It is a drinking-water tool, not a whole-house fix.
Often worth it when
- TDS is high, or water tastes salty, metallic or flat
- A test shows a contaminant RO systems are certified to reduce, such as nitrate or arsenic
- You want filtered water for drinking, cooking, coffee and ice at one tap
- You are buying bottled water for drinking
Probably not needed when
- Chlorine taste is the only complaint; carbon is simpler
- The problem is hardness throughout the house; softening addresses that
- You want treated water at every tap; RO serves one
- There is no room or drain connection under the sink
Getting a test
Three ways to find out.
Your utility’s report
On public water, your utility publishes a Consumer Confidence Report every year. It is free and a good start, though it describes the system, not your faucet.
A certified laboratory
For a sample from your own tap, use a state-certified lab. In Georgia, county offices of UGA Cooperative Extension can help arrange household water testing.
Home test strips
Useful for a quick read on hardness, chlorine and pH. Less precise than a lab, and they do not cover everything.
Next step
Have results? We’ll read them with you.
Send your report with a few lines about the house. We will point out what matters, what does not, and which treatment options fit.