We know there have been some customers emphasizing concerns about undesirable taste and odors being encountered in the tap water.  First and foremost, please don’t be alarmed regarding the safety of the water.  Woodmoor Water is compliant with all Maximum Contaminant Levels (MCL’s) as mandated by the U.S. Environmental Protection Agency (EPA) and Colorado Department of Public Health and Environment (CDPHE), so the water is perfectly safe to drink, cook with, bath in, etc.  However, we would like to share some information with everyone regarding certain aspects of drinking water that are not health related but do cause concern for people who may be unfamiliar with the aspects of water quality.  We’ll begin with sharing some information regarding water quality challenges in general, then explain the causes of taste and odors, what we’re doing about them and what the expectations are.

Every municipal water provider in the country is required to treat and serve its public with water of such quality that it meets primary drinking water standards, this finished water (after treatment) is also referred to as drinking water, potable water or tap water.  For certain substances that may be present in the raw (untreated) source water, primary drinking water standards mandate maximum contaminant levels (e.g. maximum concentrations) that must not be exceeded for these substances remaining in the water after treatment.  Some examples of substances that have primary drinking water MCL’s include arsenic, asbestos, and cyanide.  It’s important to understand MCL’s do not mandate that drinking water be 100% devoid of these substances.  As an example, drinking water can contain up to 0.20 mg/L (parts per million) of cyanide.  MCL’s have been developed and set by the EPA based on health and science so that customers won’t be harmed by the water they consume from their water providers.  In addition to primary drinking water standards, the EPA recommends secondary maximum contaminant levels (SMCL’s) for other substances that may be present in raw water sources.  Meeting SMCL’s in the finished drinking water is not required, however that doesn’t mean they aren’t important.  SMCL recommendations are aimed at lowering concentrations of substances that create aesthetic issues such as red, brown or black discoloration of sinks/toilets or clothes due to elevated concentrations of iron and/or manganese being present in drinking water.  An example of iron/manganese staining can be observed in the picture below:

 

The discoloration that can be seen in the filter (on the right) is most likely a result of the filter capturing (and concentrating) iron and manganese residuals present in the finished water and/or homeowners plumbing.  Woodmoor’s source water contains both iron and manganese in concentrations above SMCL’s.  We do treat the source water such that the finished water does not contain iron or manganese above SMCL’s, but again, even after treatment, your tap water will not be entirely devoid of these substances, and the use of aftermarket filtering devices (like those pictured), can capture and lower concentrations of these substances even further.  Other examples include skin and tooth discoloration due to elevated levels of silver and fluoride in drinking water.  There are many more examples where maintaining concentrations of various substances below SMCL’s significantly reduces or eliminates these nuisance issues in drinking water.  The EPA has a good article on SMCL’s that can be accessed at https://www.epa.gov/sdwa/secondary-drinking-water-standards-guidance-nuisance-chemicals and we would urge all our customers to read it.    

Now let’s talk about taste and odor.  Although high concentrations of certain metals (iron and manganese being some of them) can cause finished water to exhibit unpleasant tastes and odors, the taste and odors that folks are experiencing is not being produced from residual metals, they’re being produced from organic compounds naturally present in Lake Woodmoor.  To be more specific, algae, aquatic weeds and the compounds they produce.   During the reproductive cycle of algae, taste and odor producing compounds are created, geosmin and 2-methylisoborneol (MIB) are just a few of these compounds and are often cited by water providers to be the culprits.  As algae reproduce, they release taste and odor compounds into the surrounding water and when algae die, they release even more.  In addition to algae, aquatic weeds such as elodea can also facilitate taste and odor microorganisms and generate organic compounds.  The EPA has not developed primary or secondary MCL’s regarding taste and odor causing compounds, and it remains an area in need of further study, but irrespective of MCL’s, these naturally occurring compounds are elements of any Lake’s ecosystem.  Unfortunately, aquatic ecosystems are very complex with these compounds being extremely difficult to remove, and they are also able to be sensed at extremely low concentrations.  Most people can start to detect them in concentrations around 5 parts per trillion and for people with extremely sensitive taste and odor palettes, they can be detected in concentrations as low as 1 to 2 parts per trillion (equivalent to a single grain of sugar in an Olympic-sized swimming pool).

Over the years, the Water District has implemented Lake BMP’s or best management practices and installed diffusers at the bottom of the lake in order to aerate the water column, raise dissolved oxygen levels, homogenize the water column such that temperature thermoclines are reduced and we have performed chemical treatments to both suppress phosphorous and neutralize algae.  The goal of all these activities is to disrupt algae and plant growth through direct oxidation, mixing of the water column and suppression of the food that algae need to reproduce (phosphorous).  The District been treating water from Lake Woodmoor for a long time and in the distant past the District suffered from routine taste and odor issues until Lake BMP’s were installed, starting with aeration in 2016 followed by annual springtime chemical treatments beginning in 2019.  Since 2019, it’s been our observation that only those unique individuals who have extremely sensitive taste and odor palettes could sense the taste and odor compounds in our finished water.  So far this year, it has been extremely hot and dry which creates conditions conducive to rapid algae growth.  Mother nature certainly isn’t helping us out here.  Since implementing our Lake BMP’s, the District has never had to perform a second chemical treatment in the same year, however on August 10th, the District performed a second treatment to Lake Woodmoor.  We believe this will reduce the taste and odor compounds, but it will also take some time.  We anticipate that the unpleasant taste and odor of your tap water should begin to improve in a week or two and we apologize for the inconvenience this has caused anyone.  For more detailed information regarding chemical treatment products we use, how to improve your tap water through the use of POU (Point of Use) products and to access ongoing updates from us regarding taste and odor, please visit our webpage link here https://www.woodmoorwater.com/important-information-regarding-the-taste-and-odor-of-your-drinking-water