Frequently Asked Questions

For more information on any of these or other questions contact us at 1-800-755-9295.
For other contact information visit our contact page.

How do I preserve my samples?

All of our kits include the correct amount of preservative for the amount and type of the sample. If you are not using our kit, please reference the chart.

Making Sense of Method Numbers

Why are there so many ways to get the same analytical result? Simply stated, each Federal program has its own favorite procedures written for a specific federal rule. But fear not, there is some logic to the method numbers. Look at the table bellow to determine which analytical method best fits your needs. The prefix ‘SM’ stands for Standard Methods for the Examination of Water and Wastewater, 18th Edition.

500sOrganics in Drinking WaterSafe Drinking Water Act
600sOrganics in Waters (Discharged and Waste)Clean Water Act (NPDES)
200s, 300s, 400sInorganics (Metals, Nutrients, Demand, Properties) in WatersSafe Drinking Water Act, Clean Water Act
6000s, 7000sMetals in Solid WasteResource Conservation Recovery Act, RCRA (Solid Waste)
8000sOrganic Analysis in Solid WasteResource Conservation Recovery Act, RCRA (Solid Waste)
9000sMiscellaneous Tests in Solid WasteResource Conservation Recovery Act, RCRA (Solid Waste)
SM2000sPhysical and Aggregate PropertiesSafe Drinking Water Act, Clean Water Act
SM3000sMetalsSafe Drinking Water Act, Clean Water Act
SM4000sNon-metallics (Nutrients and Minerals)Safe Drinking Water Act, Clean Water Act
SM5000sAggregate Organics (Demand,Oil,Grease,etc.)Safe Drinking Water Act, Clean Water Act
SM6000sNon-aggregate Organics(Volatiles,Pesticides,etc.)Safe Drinking Water Act, Clean Water Act
SM7000sRadioactivitySafe Drinking Water Act, Clean Water Act
SM9000sMicrobiologicalSafe Drinking Water Act, Clean Water Act

Why does my water smell like rotten eggs?

Your water may smell like rotten eggs because the chemical that causes the odor is the same as that in the eggs, namely Hydrogen Sulfide (H2S). Hydrogen Sulfide is a volatile gas. Sulfides are produced in environments where oxygen is low. This low Oxygen condition is often referred to as a reducing environment. Other forms of Sulfides that produce the rotten egg odor are Manganese and Iron. There are certain bacteria that produce sulfides known as sulfur reducing bacteria. To determine if you have Hydrogen Sulfide in your water, just send us a sample.
Sulfides can be treated by one of three ways:

  1. Remove one of the reducing conditions by killing the sulfur reducing bacteria
  2. Oxidizing the sulfur to a form that does not produce the odor such as ozonation or chlorination
  3. Stripping the sulfides out of the water by air sparging.

What is the blue-green stain in my sink?

If you have copper pipes the colored stain is a dissolved form of copper being deposited on lighter colored surfaces. It is usually caused by corrosive waters that have low pH (acidic) and often have a low mineral content. Water is called the ‘universal solvent’ for a good reason. Water that has a low mineral content and is only slightly acidic will dissolve anything it can. If left unchecked the corrosive water will eat through your copper pipes.

One method of treatment is to ‘lime’ the water. This increases the pH and adds calcium minerals that will tend to deposit on the pipes instead of allowing the water to corrode the pipes. To find out if your water is acidic or alkaline, just send us a sample.

What is the white residue in my sink or on my drinking glasses?

This white residue is typically the result of ‘Hard’ water. The deposits are often made up of calcium and magnesium carbonates, also known as limestone or dolomitic limestone if it contains magnesium. You can test your water for hardness by sending a sample to us.

What is the black ‘sand’ in my water aerator screens? What is the black or gray stain in my sink?

This black ‘sand’ or gray and black stain is most likely manganese. We can test your water for manganese and other contaminants.

This type of problem is usually treated by using a water softener or by sand filtration after the manganese has been oxidized.

What is electrical conductivity?

Electrical conductivity is also known as conductivity or specific conductance. It is a measure of the ease of the flow of electricity. For those that understand electricity, conductivity is the mathematical inverse of electrical resistance. It is used to help determine the total amount of dissolved salts in water because it is related to the total amount of dissolved ions (electrolytes) in solution. For instance, pure water has a very low conductivity because water is a poor conductor though if you add a teaspoon full of table salt (Sodium Chloride) the conductivity will sky rocket. A value of 700 uS/cm is the maximum contamination level in drinking water. If you’d like to know about electrical conductivity in your water, Edge Analytical can help.

You can reduce the conductivity of water by distilling it or by a process known as reverse osmosis (R.O.).

What is hardness?

Hardness is property of water that tends to precipitate soaps and deposits white residues on various surfaces. There is no known health problem associated with hard water, it is just a nuisance. Levels of approximately 70 mg/L (4 grains per gallon, gpg) are considered hard. You can convert mg/L (parts per million) to gpg by dividing mg/L by 17.1.

You can test your water for hardness by sending a sample to us, and it can be treated by water softening.

What do all these acronyms stand for?

PQLPractical Quantitation Limit is the lowest concentration at which a chemical or property can be measured or quantified by a specific method.

MDLMethod Detection Limit is defined as that concentration at which you are 99% certain that the value is greater than zero. If the observed result is between the MDL and the PQL values are flagged as estimated values, or ‘J’ values. The ‘J’ flag comes from the word judgment meaning you are reporting the value as a judgment call. MDLs are statistically derived using analyte spiked laboratory reagent water. Proper consideration should be used when using ‘J’ flagged data with relation to real-world samples.

MCLMaximum Contamination Level is the highest concentration of a contaminant that is considered to be safe.

Why is there no MCL for sodium?

EPA has not established a maximum contamination level (MCL) for Sodium in drinking water. They have however, published an advisory level of 20 mg/L for those individuals that may have high blood pressure concerns.

Where can I learn more?

Safe drinking water act –
Public Water Systems –
Bottled Water –
Helpful Links – Resources

What do my results mean?

If you need information regarding individual results, please call us so we can help you. 1-800-755-9295

If you have the reference number of your sample, that will allow us to assist you most effectively. If you don’t have this reference number, any information such as client name or sample date will also help!

What are Coliforms? Are they like E.coli?

Coliforms are a large group of bacteria that are common in the environment and are generally not harmful. Their presence usually results from a problem in the water system and can mean that other contaminants and germs could enter the water. E. coli and fecal coliforms come from human and animal wastes. These bacteria can cause illness.