DEAR DR. BLONZ: With all the attention being given to safe water and the events in Flint, Michigan, I wanted to know the differences between the types of filtration and disinfection performed by cities and personal water systems that hook on the water tap, or those that go into pitchers that stay in the refrigerator. Is chlorine safe for city systems? Can we rely on those home systems to filter out all the unwanted substances that make it to the tap? -- T.S., via email
DEAR T.S., Many factors can affect the safety of one's home water supply. For those living in industrial or agricultural areas, there can be risks of unwanted contaminants working their way into the groundwater. But even if the water meets all safety standards, as we have learned from the Flint experience, lead in pipes or faucets could be releasing that dangerous heavy metal into the water you use.
Chlorine is a very effective disinfectant, and it has been used for almost 100 years to help destroy micro-organisms that can infect public water. Guidelines must be carefully followed, as chlorine can react with natural materials or man-made pollutants to form mutagenic and carcinogenic compounds. These byproducts of chlorination have the potential to increase the risk of certain cancers, but it is doubtful that we will be seeing a cessation of chlorination anytime soon, as it represents the most economical and effective method of control at the present time.
There are plenty of home water treatment devices on the market, ranging in price from the tens to the thousands of dollars. It is only after you know more about the quality of your water supply that you can make a decision whether and what additional purification might be needed, and which system would be best suited to your needs. Inexpensive tap or cartridge filters, for example, can grab most of the chlorine and some heavy metals and improve the taste, but check carefully, as devices vary in their ability to handle lead.
The prudent first step is to request the annual report of water quality from the department that supplies the water to your house. The report should let you know where the water comes from, and there should be a complete list of potential contaminants, such as pesticides, herbicides, bacteria, metals, industrial chemicals and radioactive substances. These reports should be sent to the person paying the water bill, so if that is not you, you should seek out the appropriate individual and make sure that you are in the loop when the report is received.
There is always an option to have your water tested; this option might be of particular relevance to those using well water, or if your location is one subject to atypical factors, such as being close to a source of pollution that does not affect the entire water supply. If you decide to go this route, seek out an independent testing laboratory.
Whatever you are considering, I suggest you get up to speed on the issues by consulting the Environmental Protection Agency's page devoted to drinking water (www.epa.gov/your-drinking-water).
Send questions to: "On Nutrition," Ed Blonz, c/o Universal Uclick, 1130 Walnut St., Kansas City, MO, 64106. Send email inquiries to email@example.com. Due to the volume of mail, personal replies cannot be provided.