All water tanks accumulate sediment over time. The soft sediment in the floor of water tanks and towers becomes a safe habitat for bacteria, protozoa and even VIRUSES! *** see reference at bottom of the page.
Out of sight out of mind-
No one thinks about the sediment. Most have no idea it is even there.
Not the water utility administrators, not the mayor not the elected city council members. Many times elected officials vote to clean or repaint the exterior of a water tower and never consider the inside condition. The popular view is that Pure Treated drinking water is pumped into the water storage tank or tower where it is held, until the end user opens a tap at their kitchen sink and gets a glass of crystal clean water.
The Truth-
All water distribution systems accumulate sediment in tanks over time.
The water is often tested daily, if the chlorine residual goes down – operators do not ask why, they just add more chlorine, over time the additional chlorine breaks down and itself becomes a contaminate in the tank that can cause cancer. *** See References below
Instead of constantly adding more and more treatment chemicals, simply cleaning the sediment from the floor of the tanks is the solution.
A countless number of biological contaminates can use the sediment in the floor of water tanks and towers to get a foot hold in a municipal drinking water system and grow into a real health concern. Why should we care what is on the bottom of a water storage tank?
We drink off the bottom of water storage tanks! Of course like many things the adverse health effects are unequally distributed to poor communities where drinking store bought bottled water is not a given, It is also these communities who have underfunded water systems that suffer from lack of maintenance.
Many utility systems that can afford inspection and cleaning of their systems simply do not allocate the funds for it because there are no regulations requiring them to do so.
In Texas yearly inspections of water storage tanks and towers are required.
Tanks get inspected in Texas. The problem in this state is there is no rule or regulation requiring tanks to be cleaned. So while thanks get inspected every year, most are seldom if ever cleaned.
The AWWA (American Water Works Association) recommends that water storage tanks be cleaned every 3 to 5 years or as needed. The EPA has published multiple white papers about contamination public water systems and the importance to keep tanks free of sediment.
Few ever read EPA white papers and AWWA recommendations are largely ignored when there are no rules or regulations backing them up.
Of course there is always someone who is doing the right thing out there, just because it is the right thing to do. In this case that would be the City of Arlington, Texas.
According to surveys conducted by the Environmental Working Group, Arlington, Texas has The best water in the United States, probably making it the best water in the world. Arlington is located in the middle of the DFW metroplex getting its water from the same source as 50 other systems. The water is treated in two water plants using similar treatment chemicals and methods as surrounding systems.
What sets them apart? For the past 18 years But they have made a commitment to keep their tanks clean, Every year a Potable Water Dive crew is contracted to vacuum the tanks clean while they remain full of treated drinking water. The divers literarily clean dust from the floor of water storage tanks, while surrounding cities allow multiple inches to accumulate before cleaning.
Too many water utilities in this country have no idea how much sediment if any is in the floor of their water storage tanks because they have never hired an inspection crew with underwater cameras to check it out. It is never thought of so they stay caught in the cycle of adding more and more treatment chemicals when contamination is detected.
Lack of regulations in this overlooked undervalued part of our infrastructure is needlessly putting millions of people at risk for illness, cancer and even death. When the solution is as simple as cleaning the floor of a storage area. It just so happens that this area stores water, and it is often 150 foot or more up in the air.
The City of Arlington has proven the effectiveness of keeping water storage tanks clean,
According to the research I did for my book “Inspecting and Cleaning Potable Water Storage” the majority of states do not have regulations requiring inspection or cleaning.
Do you think the EPA should require tanks to be Cleaned?
Take the poll : CLICK HERE AND TAKE THE POLL AT THE BOTTOM OF THIS BLOG
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This is a vastly complicated subject, that can be pulled down to three very simple terms.
- If you have a water storage tank or tower in your town there is sediment in it.
- Sediment bad,
- Remove Sediment and you remove the inorganic contaminates the habitat that organic contaminates can grow in.
See other videos and Vote Me Up! at http://current.com/users/ronperrin.htm
*** Quick Reference:
See: Disinfection byproducts list at: http://water.epa.gov/drink/contaminants/index.cfm#Byproduc
Reference: Health Risk From Microbiological Growth and Biofilms in Drinking water Systems. Published by the EPA office of Water June 17, 2002.
http://www.epa.gov/ogwdw/disinfection/tcr/pdfs/whitepaper_tcr_biofilms.pdf
QUOTE:
PAGE 26 G. Sediment Accumulation
Significant microbial activity may occur in accumulated sediment (USEPA, 1992b). Organic and inorganic sediments can also accumulate in low-flow areas of the distribution system, and enhance microbial activity by providing protection and nutrients (USEPA, 1992b). Biofilms that slough can accumulate in the periphery of distribution systems leading to sediment accumulation and the proliferation of some microorganisms (van der Kooij, 2000). Sediments may be an important source of nutrients in open finished water reservoirs, by accumulating slowly biodegrading materials which
are then broken down and released into the water column (LeChevallier, 1999b). The opportunities for biofilm development may be more abundant in storage tanks than in distribution system piping. Frequently, water is drawn from storage tanks only when water demand is high, such as during drought, fire flow, and flushing operations. This intermittent use results in prolonged storage times that may lead to increased sediment accumulation and lack of a disinfectant residual in the finished water storage vessel. Biological and aesthetic effects can be observed following the release of accumulated sediments from low flow areas of the distribution system (Geldreich, 1990).
Many studies have identified microbes in accumulated sediments, including both pathogens and non-pathogens. These include bacteria, viruses, protozoa, algae, fungi and invertebrates. Opportunistic pathogens that have been detected, and can multiply in sediments, include Legionella and mycobacteria (van der Kooij, 2000). Some primary pathogens can also survive for some time in sediments. Hepatitis A virus survived more than four months in sediments at both 5/C and 25/C (Sobsey et al., 1986). Other opportunistic pathogens found in sediments include Pseudomonas fluorescens
and Flavobacterium spp. (Berger et al., 1993). Sediments can also release nutrients into the water which stimulate biofilm growth downstream (LeChevallier, 1999b).
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Page 34 I. Proper Storage Vessel Management and Alteration
Proper storage vessel management and alteration, when necessary, can prevent contamination of the distribution system. Following TCR violations in 1996 in Washington D.C., one measure that proved effective in bringing the system back into compliance was the cleaning, inspection and disinfection of storage tanks and reservoirs (Clark, et al., 1999).
END QUOTE
EPA considering requiring all Water Storage Tanks to be cleaned!
In July of 2010 the EPA requested comments on proposed changes to the
Total Coliform Rule. The entire posting can be read on this link.
Federal Register / Vol. 75, No. 134 / Wednesday, July 14, 2010 / Proposed Rules
I have posted the most interesting part (at least to me).
2. Storage Tank Inspection and Cleaning EPA requests comment on the value and cost of periodic storage tank inspection and cleaning. There are instances of storage tanks being the source of waterborne disease outbreaks at PWSs. In December 1993, a Salmonella typhimurium outbreak in Gideon, Missouri resulted in over 600 people affected by diarrhea, 31 cases of laboratory-confirmed salmonellosis and seven deaths of nursing home residents who had exhibited diarrheal illness (four deaths were confirmed by culture). The larger of the two storage tanks had a breach in the roof hatch that allowed pigeon droppings to be carried into the tank and likely accumulated in the several inches of sediment. This contaminated sediment, more than likely, was pulled into the distribution system by a flushing program that drained the tank (Clark et al. 1996). Salmonella typhimurium was isolated from the sediment of one of the towers, and tap water tested positive for fecal coliforms (CDC 1996). In March 2008, Alamosa, Colorado (with a population of about 9,000 people) experienced a waterborne disease outbreak associated with Salmonella. The report released by the Colorado Department of Public Health and Environment (Falco and Williams 2009) indicated that the outbreak resulted in 442 reported cases of illnesses, 122 of which were laboratory confirmed, and one fatality. The State epidemiologist estimated that a total of 1,300 people may have been ill. Two storage tanks in Alamosa had several inches of sediment and breaches; one tank had breaches large enough for birds and animals to enter. Some of the key factors that contributed to these two outbreaks include significant levels of sediment (several inches to feet) and the presence of breaches of the integrity of the storage tank. Sediment accumulation occurs within storage facilities due to quiescent conditions which promote particle setting. Over time sediment continues to accumulate in a tank, even if the finished water is consistently treated tobelow 0.1 nephelometric turbidity unit(NTU). For surface water systems, it isnot uncommon to have 1⁄4 to 1⁄2 inch or more of sediment accumulate after two to three years (Kirmeyer et al. 1999).
While there are no turbidity regulations for ground water systems (except for ground water under the direct influence of surface water (GWUDI)), the levels of turbidity can be significant in the water pumped from an aquifer. Sand particles, if allowed to accumulate, provide pore spaces that house diverse populations ofbiota (which may include pathogenic microorganisms) (Kirmeyer et al. 1999; van der Kooij 2003). Periodic high flows in the storage tank may scour, stir up, and suspend the sediment (along with entrapped bacteria and pathogens) and carry it into the distribution system, with greater accumulation of sediment being a more significant concern. Other water quality problems associated with sediment accumulation include increased disinfectant demand and disinfection byproduct formation. The storage tank’s vulnerability to contamination increases when breaches of the storage tank allow insects, animals, and birds and their associated diseases to enter. Contamination from bird and other animal excrement can potentially transmit disease-causing organisms to the finished water. Waterfowl, for example, are known carriers of many different waterborne pathogens including Vibrio cholerae(Ogg et al. 1989). Based on the potential public health implications associated with poorly maintained storage tanks (e.g., as indicated by significant sediment accumulation and breaches), EPA is interested in receiving comments and supporting information regarding the state and condition of tanks that have been cleaned and inspected, costs of storage tank inspection and cleaning, and how public health can be better protected. EPA requests information on whether there are States that recommend or require periodic inspection and cleaning of storage tanks. If so, what are the requirements, the frequency of inspection and cleaning, and how successful are they? Are inspections and cleaning done by individual PWSs or by contractors?
End
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The EPA extended the comment period until October 13, 2010.
Photos & comment from Ron Perrin:
Sediment Being removed from the floor of a water storage tank
Three inches of sediment being removed from a water tower.
Over time sediment builds up in almost all water storage tanks. Only with annual inspection of the tanks can the utility operators know they have a problem with sediment levels or a possible breach in the tank. The most common breach is missing or corroded vent screens. In areas in the US where tanks are rarely or never inspected it is more common to see water storage tanks & towers with holes in the roof allowing insects and birds to enter the tank.
This sediment that builds up in the floor of the tank can become a breeding ground for bacteria, protozoa and even viruses. As contaminants become a problem, the water utilities add more and more chlorine and other treatment chemicals. This kills living organisms but starts to build up chemical byproducts like chloroform, trihalomethanes, bromoform, and other contaminants that have been linked to cancer.
Removing the sediment in the floor of water storage tanks is the best way to keep them healthy. It takes less treatment chemicals, less treatment chemicals means less chemical by-products in our water. Please join me in responding to the EPA request for comment. Let them know there should be rules to inspect and clean all water storage tanks that serve water to the public.
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Related Information:
The New York Times has a series of articles called “Toxic Waters” about the worsening pollution in American waters and regulators’ response. Read more at this link:
That Tap Water Is Legal but May Be Unhealthy By CHARLES DUHIGG Published: December 17, 2009
What’s in Your Water
The 35-year-old federal law regulating tap water is so out of date that the water Americans drink can pose what scientists say are serious health risks — and still be legal. Examine whether contaminants in your water supply met two standards: the legal limits established by the Safe Drinking Water Act, and the typically stricter health guidelines. The data was collected by an advocacy organization, the Environmental Working Group, who shared it with The Times. See the link below:
What is in your water? Find water Quality reports here: