Penn State Extension says whether a supply is labeled soft or hard depends on the presence of two highly soluble minerals, calcium and magnesium. A lab report or utility report gives the level in one of two units, or both, and they convert with a single approximate factor. This page explains the units, sets out the classes two Extension sources use, and records where those sources disagree.
The Two Units
Penn State Extension says the measure is expressed either as parts per million of calcium carbonate or as grains per gallon. Parts per million is equal to milligrams per liter, so a report in either is reporting the same measure. A grain per gallon is used exclusively as a hardness unit and, in Penn State’s words, equals approximately 17 mg/L or ppm. Virginia Tech Extension’s table puts 1.0 grain per gallon at 17.1 mg/L.
To convert, multiply the per-gallon figure by about 17 to get milligrams per liter, or divide milligrams per liter by about 17. Those are approximations, which is why published tables round and the boundaries below differ slightly by source.
The Classes
Penn State and Virginia Tech print the same five classes with the same boundaries. The table below reproduces the shared figures, and the units match the two columns of a typical report.
| Class | Grains/gal | mg/L or ppm |
|---|---|---|
| Soft | Less than 1.0 | Less than 17 |
| Slightly hard | 1.0 to 3.5 | 17 to 60 |
| Moderately hard | 3.5 to 7.0 | 60 to 120 |
| Hard | 7.0 to 10.5 | 120 to 180 |
| Very hard | Greater than 10.5 | Greater than 180 |
Have a number and a question about your heater? Call (717) 500-8528.
Where The Sources Differ
Penn State’s own pages draw the line for “soft” in two places. Its water softening article classifies water as soft below 17 mg/L. A second Penn State page, on water tests for households on public supplies, says water is considered soft if it contains less than 60 mg/L of total hardness, which is where the softening article starts its “moderately hard” class. Both pages agree that more than 180 mg/L is very hard. We record the difference and do not choose between them; if a report labels your water, check which scale it uses.
What The Number Is For
The sources tie the number to problems, not to a pass-or-fail grade. Penn State says levels below 7.0 gpg will probably not cause major scaling and soap film, and that homeowners often begin to complain when water exceeds about 120 mg/L of hardness. Virginia Tech says water hardness levels less than 7.0 gpg or 120 mg/L generally do not require treatment, and that treatment is only necessary when the hardness level is causing a problem. Penn State also notes there are no federal or state standards for hardness in water. What the deposit does at a water heater is in our effects guide, and the report itself is covered in our testing guide.
What This Page Will Not Tell You
It will not tell you how hard your water is. We publish no mineral-level figure for Lancaster, for any township, or for any utility, because the utility serving an address, or a private well, determines it and none of the sources above speaks to Lancaster County. For maintenance questions once you do have a number, see water heater maintenance in Lancaster, PA.
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What does the abbreviation on a mineral report stand for?
GPG means grains per gallon of calcium carbonate. Penn State Extension says a grain per gallon is used exclusively as a hardness unit and equals approximately 17 mg/L or ppm. It is one of the two units a report may use.
How do I convert between the two units?
Divide milligrams per liter by about 17 to get grains per gallon. Penn State gives the factor as approximately 17 and Virginia Tech’s table puts 1.0 grain per gallon at 17.1 mg/L. Parts per million is equal to milligrams per liter, so ppm converts the same way. Treat results as approximate.
Which class counts as the upper end?
Penn State and Virginia Tech both class 7.0 to 10.5 grains per gallon, or 120 to 180 mg/L, as hard, and more than 10.5 grains per gallon or 180 mg/L as very hard. The two sources agree on those boundaries. Penn State’s separate public-supply page defines soft differently from its softening article; see the section above.
Are the minerals in tap water bad for you?
Penn State Extension says that from a health standpoint calcium and magnesium have no adverse effects. Virginia Tech Extension says hard water is considered safe for drinking and household use. The concern is deposits and soap performance, not health.
What do the sources say about Lancaster-area water?
Nothing, and we publish no figure for it. A figure for one utility or well does not apply to another address, and none of our sources speaks to Lancaster County. Your utility’s annual report or a laboratory test is the way to find yours; see our testing guide.
Where can I get my own report near me in Lancaster County?
Start with your water supplier’s annual report or a laboratory test. Lancaster Water Heater Pros services water heaters across Lancaster City and Lancaster County. Once you have a number, call (717) 500-8528 to talk through what it means for your heater. Service requests are accepted 24/7.