Massachusetts Water Resources Authority


Pharmaceuticals and MWRA Drinking Water Sensitivity of Testing Procedures (

The testing for pharmaceuticals is extremely sensitive and the levels the testing lab is looking for are trace amounts.  The testing MWRA undertook had detection levels measured in nano-grams per liter, that is, parts per trillion. Water and wastewater professionals usually deal with milligrams and micrograms per liter – or parts per million and parts per billion. The tests for pharmaceuticals are a thousand to a million times more sensitive than the usual tests done for regulated compounds. Furthermore, when these tests are completed, we must instruct the sampler not to shower, shampoo, use any personal care products such as deodorant or perfume, avoid contact with any materials which may have antimicrobial treatments, and so on. If the samplers do not follow these instructions, we risk false positives.

For instance, in the initial raw water samples, minute trace amounts of one compound, Tris (2-Butoxyethyl) Phosphate*, or TBEP, were detected.  TBEP is a common plasticizer used in rubber gaskets and washers and may have been introduced into the sample from the plant’s internal plumbing system. In fact, the National Library of Medicine notes that it is used in “synthetic rubber intended for contact with food or drink.” It is also is a flame retardant used in floor polishes.  MWRA re-tested the raw water for this compound taking samples directly from the reservoir (i.e. not through the plumbing) and no trace was found in the follow-up samples.

Rev. September 4, 2008

Historic Withdrawls Reservoir Levels