What Determines water Quality? Well Maintenance Well water Testing AZ survey on individual systems water quality Final remarks

Transcription

1 Private Water Wells 1# 1 Overview Numbers Regulations What Determines water Quality? Well Maintenance Well water Testing AZ survey on individual systems water quality Final remarks

2 Private Wells In AZ and US 2# 1 Over 100,000 wells in AZ (source:adwr) ~5%+ of the population Rate of construction (>3000/year) (source:adwr) Over 46 million in the US ~13+%+ of the population Well owners are on their own because: There are no water quality regulations Owners must test and monitor their well water quality Costs of construction, testing and maintenance are owners responsibility

3 Requirements 3# 1 Private Wells defined as: Up to 35gpm, domestic use only(exempt wells) Notice of intend to drill required by ADWR All other wells require a permit from ADWR As of Dec, 2005 no new wells allowed within AMAs, with some exceptions. See exempt wells fact sheet S.B Well replacement Const. costs exceed hookup to municipal provider Access issues..

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5 Well Water Quality I 5# 1 What determines well water quality? Geology-environment-location Shallow-deep (more-less responsive water quality changes) Mineral composition (variable.. calcareous, metals..) Natural recharge (nitrates,salts, OM?) Human activities Septic fields, common sources of nitrates, pathogens.. agricultural activities, irrigation practices (nitrates..pesticides..) Industrial activities, mining, (solvents, metals ) Storage (fuel tanks) (gasoline hydrocarbons) Urban runoff and seepage (hydrocarbons such as VOCs..)

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11 Water Quality Standards-Guidelines 11 Background 1914, first biological standard (used at all levels) 1974, The Safe Clean Water Act (fed. aut. set/enf. Stds MCLs) Secondary Standards (guidelines) Non-enforceable- aesthetic, cosmetic, delivery ph, salinity(tds), fluoride, Copper, Iron, organic matter Primary Standards Enforceable- maximum contaminant limits (MCLs) Over 90 individual+classes of contaminants. Inorganic (As, Pb), organic (TCE, pesticides), pathogens

12 Well Water Quality II 12 Well Construction See Well Owner s Guide (source:adwr) Must Follow ADWR AZ State standards. AZ Licensed driller Location Surface seal + construction materials (steel or PVC) Well disinfection (follow ADEQ guidelines) Water quality testing: NONE required, recommends use of State certified lab. Reports (driller, well logs.. pump installation)

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14 Well Water Quality Information 14 Starts at the surface Previous owners Your own well history,construction date, materials, maintenance, water treatment units.. Neighbors Obtain their water quality history Public water provider(s)-nearby. Detailed water quality reports and history, obtain annual water quality reports (right-to-know law) ADEQ, ADWR, USGS Aquifer: flow direction, depth Geology:general water quality, natural contaminants Nearby potential sources of contaminants.

15 Well Maintenance I 15 and maintenance None explicitly required, thus; Owners should be familiar with their well s construction materials, design, pump, storage and distribution system. Owners should be vigilant about any taste,smell, visual water quality changes and should follow and water the annual water testing protocol (discussed next) Well components, screens, casings, pipes, pumps, tanks degrade over time and release contaminants into the water. (iron, zinc, copper, plasticizers, oil, bacteria..) ADEQ website provides two fact sheets In case of flooding In case of fire Both include emergency water disinfection steps.

16 Well Maintenance II 16 Shock Chlorination: Caution! Used to disinfect wells, during and after construction and as needed to remove microbial contaminants. Guidelines available: AZDEQ, AZ Coop. Ext. Water Facts No. 5. Dangerous chemicals (strong liquid bleach) Preliminary research suggest that Arsenic (As) may be released from aquifer materials and pipes during shock chlorination. Best to use ph neutral bleach solutions (6-7). Test for As after shock chlorination (if you live in area high in As).

17 Well Water Testing I 17 At a minimum, domestic wells should be tested annually for the presence of coliform bacteria as an indicator of pathogens. More frequent testing is suggested if visual changes in the water quality are noticed or if unexplained health changes occur. If positive, test again to verify and consider shock chlorination of the well and/or delivery system. Shock chlorination will not eliminate pathogens if contamination is in the aquifer water. Options: Seek alternate sources of water. Install water disinfection system.

18 Well Water Testing II Proposed schedule Initial Tests* Hardness, sodium, chloride, fluoride, sulfates, iron, manganese, arsenic, mercury lead, plus all tests listed below Annual Tests (at a minimum) Total and Fecal coliform bacteria, TDS, ph, nitrate Monthly Visual Inspection Look for and note changes in: Turbidity (cloudiness, particulates) Color, taste, and odor** Health changes (reoccurring gastrointestinal problems)*** 18 *Annual testing may not be needed, as these chemicals usually are naturally occurring and their concentrations do not change over time. **Consider one or more of the initial tests. ***Annual testing should begin immediately.

19 Water Testing Costs 19 Highly Variable Basic water quality parameters, including total+fecal coliform bacteria (NPDWS and NSDWS) ~$ /sample Include:pH, salinity, hardness, major cations (Sodium..) and anions (Fluoride,Chloride, Nitrate, Sulfate..) Specific contaminants (NPDWS) ~$ /sample, depending on number and types of pollutants. Include: arsenic, lead, mercury, pesticides, VOAs, DBPs. uranium )

20 Water Testing Tips I 20 If contamination from storage and delivery system is suspected, collect and test water samples from the tap, storage system, and at the well head. (isolate the source) If aquifer contamination is suspected, collect several water samples at the well head, following purging and over time. (contaminant(s) levels should stay constant) Choose the list of contaminants to be tested with the assistance of a qualified water quality expert See the table of water problems and suggested tests, and review the national drinking water standards in: Arizona Know Your Water booklet and EPA website for latest revisions. Locate an Arizona state certified laboratory Call the Arizona Department of Health Services (ADHS) Bureau of State Laboratory Services for a list of certified water testing laboratories in Arizona ( ).

21 Water Testing Tips II A good water testing laboratory should provide clean-sterile containers and clear instructions on how to collect water samples. (Ext. Bul. #AZ1111) Follow water sample collection, including system flushing and well purging when appropriate, preservation and shipping instructions carefully, in order to prevent biased test results. Avoid collecting stagnant-first flush water. Well purging = pump out 3-5 wells casing volumes before sampling. Water testing laboratories must comply with state and federal guidelines by using USEPA approved methods of analysis. Guidelines for water testing are regularly published and updated by the EPA and are also listed in the Code of Federal Regulations, Title 40, part

22 Water Testing Kits Most kits relay on color changes (strips or liquid solutions) with scales. Should be based on EPA approved methods Often limited in range and may not be very precise or accurate. Use only kits from reputable independent companies. Recommend verify results with certified laboratories. Costs range from a few dollars for test strips to over one thousand for electronic colorimeters. 22

23 Water Quality: Individual and Small Systems in Arizona. (Marreno-Ortiz et al., 2007) 23 A total of 49 mostly private wells from seven counties, sampled over 14 months. 70 Samples. Major water quality parameters ph, turbidity, TOC 19 metals HTP, Total, fecal Coliforms and E.coli Five Other specific pathogenic viruses and bacteria Coliphages, Aeromonas, Helicobacter, human enteric viruses

24 Some Results 24 About 95% of the samples exceeded at least one primary or secondary DW standard 43% of the samples positive to Total Coliform. A few samples positive for Fecal coliforms and E.Coli 30-33% of the wells exceeded Arsenic (10ppb) and Aluminum Drinking Water Standards. 4-16% of the samples had levels of lead, uranium, copper and other metals exceeding Drinking Water Standards. Caution 1: These results are based on a very small fraction of the total private wells in AZ and should not be generalized.

25 Final Remarks I Private Wells construction will continue, particularly in rural AZ (outside AMAs). There are no laws that regulate private wells drinking water quality (construction, and maintenance guidelines provided by ADWR). 25

26 Final Remarks II 26 To be reasonably sure that their water quality meets NSDWS and NPDWS Well owners should: seek water quality information from neighbors, water providers and state agencies. be knowledgeable about and maintain their well systems. and routinely test their well water following the suggested testing schedule previously discussed Treat drinking water to current standards using proven treatment methods and well maintained water treatment systems, see: Arizona Know Your Water booklet).