FAQ / Household Analysis / drinking water reports for your homeFAQ / Household Analysis / drinking water reports for your home

Household Analysis



There are no simple, pat answers to many of the commonly asked questions regarding the quality of your drinking water. While we believe this information is correct, we do urge you to contact your local public health officials or your physician for specific health questions or evaluation of health risks from your water supply.

The constituents of this package were chosen to address some of the most common chemical problems in Northern California well and surface waters.  These problems are:  

1. Corrosive (very soft) water

2. Hard water

3. Iron and Manganese contamination


Understanding Your Report

1. Units of Measurement

Most of the analyses in the household analysis package are measured in milligrams per liter (mg/L). This unit is also expressed as parts per million (ppm). To make an analogy, 1 mg/L (ppm) is equivalent to a distance of 1 inch out of 16 miles.  Iron and manganese are measured in micrograms per liter (µg/L) or parts per billion.

2. What do the numbers in your report mean to you?

In the following list of parameters which are included in your household analysis package you will note the column headed “MCL.”  “MCL” represents the term “maximum contaminant level”.  These levels (where they have been established) are set by the federally mandated Safe Drinking Water Act of 1977 and the California Code of Regulations Title 22.  Compare your results to the values listed under “MCL”.  If your water exceeds any of these values it would not be considered suitable for a public water supply.  However, it is perfectly legal for you to drink your own private water no matter what it has in it.  We would advise you to consider a water treatment system or an alternate water supply if your water exceeds the MCL values.  For parameters which have no MCL’s listed please see Section D for further explanation.


Parameters Included in Your Household Analysis Package


Total Dissolved Solids
Tannin & Lignin


6.5 – 8.5 pH units
None Established
500 mg/L
See Section D (8)
See Section D (4)
None Established
None Established
300 ug/L
50 ug/L
None Established


Explanation of Your Report

1. pH

The pH is a measure of your water’s tendency to be acidic or basic.  A pH of 7.0 is neutral (neither acid nor basic). This is, in general, a desirable condition. A pH of less than 6.5 is considered acidic. An acidic pH along with a low hardness value tends to be corrosive to plumbing. A slightly basic pH (up to 8.5) is not considered harmful.

2. Alkalinity

Alkalinity is a measure of the ability of water to retain its characteristic pH. This parameter is usually from about 15 mg/L to around 200 mg/L for Northern California waters. Alkalinity is mainly dependent on the concentration of carbonates and bicarbonates in your water. If you are going to have a water treatment system installed, your water system specialist will need to know the alkalinity.

3. Total Dissolved Solids (TDS)

This test measures the amount of dissolved minerals in your water. The usual TDS of Northern California drinking water is from about 80 to 200 mg/L.  Low TDS values contribute to water’s corrosiveness.  A TDS of 500 mg/L or more renders water unsuitable for use for several reasons:  1. It often tastes salty. 2. Some minerals may be contained in injurious amounts.  3. It will have a tendency to clog your pipes and may stain clothes, sinks, etc.  4. It leaves mineral deposits on glassware and dishes.

4. Hardness

Hardness is mainly the result of calcium and magnesium dissolved in your water. Commonly accepted hardness ranges are: soft water 0-60 mg/L, moderately hard water 60-120 mg/L, hard water 120-180 mg/L and very hard water is >180 mg/L. A hardness level above 250 may not be suitable for domestic use since addition of soap to the water will result in the formation of a sticky curd rather than the hoped for suds. Large amount of soft sticky deposits will be left on plumbing fixtures and clothes. Glassware will be almost impossible to get clean. Pipes will clog up in short order. Very soft water also causes problems by corroding metal pipes and plumbing fixtures. For a further explanation of this problem see the “Corrosiveness” section.

5. Calcium and Magnesium

There is no MCL listed for either of these two elements. Both are very common and very useful in your water supply. They are required nutrients and are also responsible for protection of metal pipes from the corrosive action of water. In excess, these elements do create “hard” water as explained above.

6. Iron and Manganese

The MCL levels of these two commonly found elements are set for aesthetic rather than toxicological reasons. Iron causes a characteristic “rust”-colored cloudy appearance in water. If enough iron is present, actual rust will form and settle out.  Clothes, water fixtures, and even blond hair will be stained a rusty red color.  Manganese has similar effects except the color of the water and stain is a darker brown or even a grayish hue.  Do NOT try to add bleach to wash water in order to prevent staining by iron or manganese.  The oxygen in the bleach will cause even more “rust” to form from the two dissolved elements.  Removal of these obnoxious chemicals from your water must be accomplished by oxidation and filtration.  See your local water treatment specialist or plumber for details.

7. Tannin and Lignin

These chemicals are generally considered harmless at levels found in drinking water. They are the agents which cause the color of tea. They also are responsible for the browning of apples and potatoes upon exposure to air. At high levels they will cause your water to have a yellowish appearance. This may be distinguished from iron problems because the color of tannin and lignin in your water is crystal clear rather than cloudy, as iron would be. This test is included in our household series upon the request of water treatment specialists. These chemicals will foul some types of iron and manganese removal systems. In order to choose the proper system for your water, the tanning and lignin content must be determined.

8. Corrosivity

Corrosivity is a calculated value based on pH, alkalinity, total dissolved solids, and calcium levels. This value expresses the tendency of water to deposit or dissolve calcium carbonate on the inside of tanks, pipes, hot water heaters, etc. A slightly positive number (up to +2) for the “Langlier Saturation Index” (the term used for units of corrosivity) is ideal. This indicates a slight tendency to deposit a protective film of calcium carbonate on your pipes. This film precludes water from even touching the metal pipe. A negative Corrosivity value indicates a tendency for water to dissolve calcium carbonate. This means water is in constant contact with the piping and may begin to dissolve the copper, iron, or zinc in the pipes. Your plumbing may not last long under these conditions. Another problem caused by corrosive water is more insidious. The metals being dissolved from the pipes are being added to your drinking water. While low levels of iron, copper, and zinc are not a health problem, cadmium and chromium are.  These two heavy metals are frequently found as contaminants in zinc coated iron pipes.  At the other extreme, and not common in our area, a high positive number (greater than +2) for corrosivity indicates a tendency for water to deposit great amounts of calcium carbonate. This will eventually clog your pipes with “scale”.  Your water treatment specialist or plumber will be able to advise you on ways of alleviating these problems.


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