### Purpose of this wiki This wiki is intended to provide short, legible descriptions of common water contaminants, with a no-nonsense rundown on what methods might be used to both **assess** and **address** the presence of these contaminants. We're aiming to pay special attention to the **relative cost** and **technical expertise** required for each method. For example, some of these contaminants might be readily addressed by simple, cheap home testing kits. Some of them might currently require expensive laboratory testing. For many of them, the EPA and others have published protocols for how to assess the level of these contaminants in a laboratory setting; we'd like to begin to collect links to these protocols, labeling them as "possibly DIY?" or "DIY: implausible", etc ... Suggested format for entries: > **Name of the contaminant** > Why is it a problem? How does it enter the water supply? > How much of this contaminant is safe? > How can we measure it? Does it require a professional lab? Are there DIY techniques available? > What can be done about it? Can I filter it out of my water myself? > Links to good relevant resources, helpful agencies, and groups concerned about the issue. Please help us fill out this list with relevant info about important water contaminants ... --- ## Glyphosate #### Why is it a problem? How does it enter the water supply? Glyphosate is a commonly used pesticide sold under trademarks such as Monsanto's 'Roundup'. that enters the water supply via ... #### How much is safe? Experts disagree on safe levels; the EPA has set a legally enforceable maximum contaminant level (MCL) for glyphosate of 700 ug/l in drinking water, which is 7,000 times higher than the MCL in Europe. #### How is it tested? Possible testing methods include: a) laboratory tests, for $200 - $300 (links to more info) b) spectroscopy (see Public Lab's Spectroscopy Kit) (links more info) ; c) conductivity (see Public Lab's Riffle) (links more info) d) paper chromatography tests (see the following four kits, available online) (links to more info) #### What can be done about it? #### Links to more info http://www.organicconsumers.org/articles/article_29696.cfm --- ## Endocrine disruptors --- ## Mercury --- ## Arsenic --- ## Lead --- ## Oil and Grease -TPH Volatiles -TPH Gasoline -TPH Diesel and Oil ##Nitrogen: Nitrates, Nitrite, Ammonia, & Ammonium Nitrates, Nitrite, Ammonia, & Ammonium are "fixed" forms of nitrogen available to living organisms, and represent different stages of nitrogen in the [nitrogen cycle.](https://en.wikipedia.org/wiki/Nitrogen_cycle) Nitrogen is a major limiting nutrient in plant growth-- when nitrates occur in large quantities in water from fertilizers, manure, or sewage runoff, they can cause algal blooms that create dead zones. Nitrates have also been linked to increased risks of [cancer, and complications with a number of diseases, including asthma](http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1310926/). The EPA limits drinking water concentrations of Nitrates to 10mg/L or lower, however, health threats can occur even at those levels. Ammonia (NH3) and ammonium ion (NH4+) are related chemically by an acid / base reaction: NH3 + H+ <=> NH4+ The equilibrium between ammonia and ammonium is pH dependent, with the two species being at the same concentration only under fairly alkaline conditions, pH = 9.25. At neutral pH, the concentration of free NH3 is less than 1% that of NH4+. Since this is the case, the concentration of ammonia is usually not significant and can be determined from the concentration of ammonium and the pH. ####Assaying Nitrogen The wet lab [Kjeldahl Method](https://en.wikipedia.org/wiki/Kjeldahl_method) is often used to get the measurement TKN, or Total Kjeldahl Nitrogen. [EPA Method 353.2](http://water.epa.gov/scitech/methods/cwa/bioindicators/upload/2007_07_10_methods_method_353_2.pdf) involves a cobalt catalyst and spectroscopy in the visible range. #####UV Spectroscopy [In Situ Underwater Spectroscopy (UV in the ocean):](http://www.mbari.org/chemsensor/ISUShome.htm) [Ultraviolet spectrophotometric determination of nitrate: detecting nitrification rates and inhibition. Kelly RT 2nd, Love NG. Water Environ Res. 2007 Jul;79(7):808-12.](http://www.ncbi.nlm.nih.gov/pubmed/17710926) TSS, BOD, and Nitrate with a single 200nm-720nm spectrometer [ON-LINE NITRATE MONITORING IN SEWERS USING UV/VIS SPECTROSCOPY F. Hofstaedter, T. Ertl, G. Langergraber, W. Lettl, A. Weingartne](http://www.s-can.fr/medialibrary/publications/p_2003_02.pdf) #####Potentiometric Measurements of Nitrate and Ammonium using Ion Selective Electrodes Ion selective electrodes (discussed [here](http://en.wikipedia.org/wiki/Ion_selective_electrode)) can be used to conveniently measure ammonium and nitrate. These electrodes behave similarly to commonly used pH electrodes. The main difference between a pH electrode and an ion selective electrode (ISE) is that the former has a glass surface that is electrically polarized by protons and the latter has a membrane that is responsive to the ion in question. Like a pH electrode, an ion selective electrode responds to changes in analyte concentration by a measurable change in voltage. Ion selective electrodes can be measured with most pH meters. These electrodes can be purchased from a variety of sources (VWR, Fisher, etc) but are somewhat more expensive than pH electrodes. Vernier sells ammonium and nitrate sensitive electrodes ([here](http://www.vernier.com/products/sensors/ion-selective-electrodes/)) for $179 each.