What type of water supply is your house on?
LARGE MUNICIPAL SUPPLY - (city water) > 50,000 People
Large public supplies serve densely populated urban and suburban areas. They draw from reservoirs and rivers, and may also tap into groundwater reserves. Because they draw large amounts of water from a variety of sources, these supplies are not very vulnerable to small local sources of pollution. Further, they are regulated fairly closely with substancial testing requirements. Therefore, it is unlikely that you will drink unsafe levels of environmental contaminants.
The one possible exception has to do with chlorine, the agent used to keep the water free from harmful microbes. Chlorine converts to trihalomethanes (THMs), chemicals that are suspect carcinogens and reproductive toxicants. While it is important to have the water supply disinfected with chlorine, it is a good idea to drink as little of the THMs as possible. The federal limit for THMs in drinking water is 80 ppb. This value has been questioned by health effects in some studies and most public systems can provide water that has much lower THM levels.
IN THE CASE OF A LARGE MUNICIPAL SUPPLY SYSTEM, read your water company's report card, the Consumer Confidence Report (CCR). This is public record and available upon request.HOW TO INTERPRET THE CCR Report
THe CCR will have columns showing you which chemicals were detected in your water over the course of a year, their levels in the water, and the federal drinking water standard (MCL). Most MCLs are set in a conservative, health protective manner so that levels below the MCL are not considered a health risk.
Are the chemicals in your water within 50% of the MCL?If yes, this is a potential concern because levels can fluctuate.
Find out if the company is doing the extra testing required of such findings.
Are the total THMs above10 ppb?If yes. this is cause for some concern due to theoretical cancer and reproductive risks, even
though the federal limit is 80 ppb.
WHAT YOU CAN DO
For THM results over 10 ppb consider filtering your drinking water with a granular activated carbon (GAC) filter to remove THMs. This will also filter our many other chemicals that may occur in the water.
If metals such as arsenic are within 50% of the MCL, you may want to filter the metals out as well. However, the filter may be different than for THMs.
For more information on water filters, public water supplies, and test results see out book WHATS TOXIC WHATS NOT. You can also get helpful information from the
USEPA and the
NSF. MEDIUM-SIZED WATER SUPPLY - 3,300-50,000 people)
Medium-sized supplies usually service some part of a city or an entire town up to 50,000 residents. They may rely upon surface or groundwater reserves and generally have similar characteristics as the larger supplies. There follow the advice above on the larger supplies and ask to see your town's CCR.
SMALL PUBLIC SUPPLY - (15-3,300 people)
Small public supplies usually service a cluster of customers such as an apartment complex, small neighborhood or shopping plaza. This exists in rural or suburban areas not serviced by larger systems. Small systems generally rely upon groundwater. Since they draw a limited amount of water and from only one source area, these systems are more susceptible to localized pollution. In addition, testing requirements are often less stingent (less frequent and fewer chemicals tested). These systems will also have chlorine by products (THMs) just as in the bigger system.
Because testing may not be as stringent as in the larger municipal supplies, here is what you can do.
Get your town's CCR (Consumer Confidence Report).
THe CCR will have columns showing you which chemicals were detected in your water over the course of a year, their levels in the water, and the federal drinking water standard (MCL). Most MCLs are set in a conservative, health protective manner so that levels below the MCL are not considered a health risk.
Are the chemicals in your water within 50% of the MCL?
If yes, this is a potential concern because levels can fluctuate.
Find out if the company is doing the extra testing required of such findings.
Are the total THMs above10 ppb?If yes. this is cause for some concern due to theoretical cancer and reproductive risks, even though the federal limit is 80 ppb.
Is the supply well within 1/4 mile of a gas station, landfill, dry cleaning shop. toxic waste site, agricultural fields, greenhouses or industry?
If yes, this is a cause for concern since these are all potential sources of groundwater contamination.
For THM results over 10 ppb consider filtering your drinking water with a granular activated carbon (GAC) filter to remove THMs. This will also filter our many other chemicals that may occur in the water.
If metals such as arsenic are within 50% of the MCL, you may want to filter the metals out as well. However, the filter may be different than for THMs.
If the supply is close to potential sources, find out how often the company tests for chemicals likely to come from these sources (E.G. gasoline, industrial solvents, pesticides). If testing is less that once every 2 years, then ask the company if they will test more frequently for these chemicals. Consider doing your own testing if the company refuses.
For more information on water filters, public water supplies, and test results see out book WHATS TOXIC WHATS NOT. You can also get helpful information from the
USEPA and the
NSF. PRIVATE WELL - (Single Household)
Private wells provide water to an individual household. This occurs in rural or suburban areas not serviced by public supplies. Private wells rely on groundater. Since they draw a small amount of water and from only one source area, private wells are the most susceptible to localized population. In addition, there are usually minimal testing requirements when the well is first installed and no requirement to test thereafter, not even when selling the property.
CONGRATULATIONS. Testing your drinking water is one of the most important things someone on a private well can do to protect his/her health. Understanding the results is fairly simple. Here are some pointers.
The report will have columns showing you which chemicals were detected in your water, their levels in the water and the federal drinking water standard (MCL). Most MCLs are set in a conservative, health protective maner so that levels below the MCL are not considered a health risk. Compare the chemicals detected in your water to the MCLs.
If there are chemicals in your water over the MCL, Immediately stop using the water, re-test and look into water filters.
Are the chemicals in your water within 50% of the MCL?
If yes, this is a potential concern because levels can fluctuate.
Find out if the company is doing the extra testing required of such findings.
Are the total THMs above10 ppb?
If yes. this is cause for some concern due to theoretical cancer and reproductive risks,
even though the federal limit is 80 ppb. Is the supply well within 1/4 mile of a gas station, landfill, dry cleaning shop, toxic waste site, agricultural fields, greenhouses or industry?
If yes, this is a cause for concern since these are all potential sources of groundwater contamination.
WHAT YOU CAN DO.
1) Put on a filter to remove chemicals in the water that are above the MCL.
Re-test to make sure the filter is working properly.
2) Re-test within 1-2 years any chemicals which may come from nearby sources (e.g. gas stations, solvents
from industries, pesticides from farms or nurseries)
4) Contact the local health department to inform them of contaminants in your well, especialy if they are over
the MCL. This may be a community problem that requires investigation by the town or state.
PARAMETERS for TESTING PRIVATE WELLS
For more information on water filters, public water supplies, and test results see out book WHATS TOXIC WHATS NOT. You can also get helpful information from the USEPA and the NSF.
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