By Shannon P. Murphy
(or it’s still not your Father’s Oldsmobile!)
Last month we reviewed some of the lab and field test data recently gathered on reverse osmosis (RO) membranes. What these revealed is that RO membranes have a very high ability to reduce and/or remove many vastly different contaminant materials from water including chemical agents, microbiological and inorganic contaminants. Of the list of contaminants that were analyzed in the various test programs including strychnine, aldicarb, MS2, PHI X 174, B. diminuta and others, mercury appears to be the one true water contaminant that proves difficult for RO to remove. On the upside, very positive results were obtained for bacteriological and virus reduction, almost to the point where the RO systems could meet the reduction criteria for those on their own to be called a purifier (six log bacteria reduction, four log virus reduction and 3.3 log for cysts).
We also demonstrated RO’s ability to reduce both forms of arsenic, arsenite (III) and arsenate (IV) in the water, which is often misconceived in the water treatment field today.
Real world applications
Over the past several years, we have been working directly with small communities, state facilities, schools and parks installing decentralized water treatment systems for arsenic, perchlorate, nitrate and fluoride compliance with point of use (POU). The size of these facilities has ranged from ultra-small (facilities with 10 connections) up to ‘large’ residential communities of 225 connections. Throughout all of these projects, one of the unexpected highlights in this program continues to be the response from the public on the quality of the water from the RO units.
Conventional thought for community water treatment is to contract with an engineering firm in order to design and bid out a complete water treatment facility. As the new regulation for arsenic is currently underway there are numerous treatment plants that have gone on line that can provide actual costs involved in undertaking this process. There are a few recent applications that speak volumes for the dilemma small communities face, like the small town of 126 homes in Southern California. This town required a $2.1 million loan for their arsenic treatment plant (that’s an extra $139 per house, per month, for 10 years). In Idaho, a town of 120 required a loan of $1.6 million, which increased the water bill from $28 to $57 a month. In Arizona, a town of 120 service connections spent over $700,000 on their treatment plant and the associated engineering, permitting, building and operator costs. In New Mexico, a community of 470 homes saw their water bill more than double – from $24 to $49 a month – to cover the cost of their new granular ferric hydroxide (GFH) water treatment plant. These are just a few of the more recent examples to hit the media.
What systems should consider POU?
POU has proven to be a low-cost alternative for communities with 300-400 hook-ups, not just for the 25 or so initially thought. This is especially true if systems have multiple water contaminant issues to address like arsenic, fluoride, perchlorate and radium, to name a few.
Before you say to yourself, “Ah ha, I have heard something about this before -it is not a program worth pursuing,” look at the real world applications. That same Arizona community that spent $700,000 to get their treatment plant up and running could have implemented a POU compliance program, completely installed, for under $40,000.
Communities consisting of all residential dwellings are especially opportune for POU applications. These communities can complete the installation of the units with in a few weeks through a number of avenues (those will be discussed below). More complex water districts that have a blend of housing, labs and offices may require a mix of POU and point of entry (POE) products. Even with this mix of products, there are significant savings to be had utilizing this water treatment approach.
What is involved initially?
In addition to the cost benefits of POU, there are a number of additional upsides to implementing a POU program in a community and various hurdles that need to be addressed. On the positive side, there is little-to-no upfront engineering cost, nor other treatment plant costs like obtaining building permits. Central treatment usually requires additional approvals needed for handling pre-treatment chemicals or other material hauling and waste removal approvals. All of which add significant cost and time to any water treatment program and create the need for higher-level operators for the facility.
Implementation of POU can easily be completed through installation of the devices in the home or office. The most significant hurdle for POU is in regards to management requirements and the education or buy-in from the community. A POU program requires access into all of the homes in the community, either by a water system employee or bonded water professional, in order to install the RO unit. In some communities this is not an issue and access is granted with ease. For other communities, this is the main sticking point which prevents moving forward, as some individuals refuse to grant access to their residences. There is also some additional documentation required, confirming that all houses have a unit installed and that proper annual maintenance is being conducted of those units.
What are the requirements?
Under the U.S. Environmental Protection Agency’s (US EPA’s) Safe Drinking Water Act (SDWA) amendments of 1996, the agency allowed communities serving fewer than 10,000 people the ability to use POU water treatment in order to achieve compliance with the SDWA requirements. Specific information regarding this can be found at the Legal Information Institute. (http://assembler.law.cornell.edu/uscode/search/display.html?terms=point%20of%20use&url=/uscode/html/uscode42/usc_sec_42_00000300—g001-.html)
The requirement set out by the US EPA for the POU program is that the devices must be certified by an ANSI -accredited body, under one of the NSF/ANSI standards as a POU device, certified for the water contaminant of concern, like arsenic. The treatment system must have a performance indication device that indicates to the user when it is time to service the unit (in some cases the indication device must not physically turn off the POU device). Additionally, most states ask for the education outreach that the community is conducting. Individual states may also require that the units be tested over a period of time in order to ensure that each device is providing safe drinking water. Typically this is completed through a blend of onsite test kits and sampling to be tested at a state-approved lab.
This is where the real issue is for many communities. How much initial, capital and annual costs are involved and does the community have the ability to cover these costs? Several different estimates regarding the use of POU RO have been published by the US EPA and other agencies. Many of these estimates are substantially higher than today’s as they were based upon much more expensive RO units that required two service calls annually.
New cost estimates utilizing low-cost, certified RO units with annual maintenance checks now average under $12 a month per service connection. Compare this 10-year cost against centralized treatment provided by an independent regulatory body and the break-even point for centralized treatment cost comes in between 440 and 480 service connections.
This is where the tie-in from the previous article and this one really takes hold. In the end, the real question boils down to this: What is the consumer really getting for all the money being spent on water treatment? Specifically, what is the value to the consumer of the water that is being provided? A large centralized water treatment plant will get the consumer arsenic-free water, but in the end, typically, that is all they will get.
Based on the lab and field testing that has been done (see last month’s article), these RO units provide several value-added components to the end user. The RO consumer is receiving arsenic- free water and also getting ‘bottled water quality’ at their tap. There is also the added value to the consumer regarding incidental water issues that arise.
One of my POU communities recently had a hit for bacteria at their well. They were required to inform all of the homeowners of the incident, as well as to provide follow-up sanitizing, monitoring and reporting; however, the entire community felt better for having the RO units. I provided the test results obtained in the US EPA/ETV report signed by the National Homeland Security research Center to the community and to their local regulatory body. Again, while it did not alleviate any of the reporting, sanitization, or additional testing, the test reports provided a level of security that there was a barrier in place to provide protection when a problem pertained to their drinking water. (author’s note: once the incident was contained, it was required that the RO units be serviced and run through a disinfection protocol .)
It is examples like this that create the positive comments from these communities because people feel they are receiving added value through the use of a POU RO unit. In many cases, the homeowner sees an overall savings as well, since they are purchasing less bottled water. In various independent studies conducted by water utilities, it was discovered that most people are as concerned with secondary water contaminates like chlorine, clarity and other tastes and odors as they are with the primary water standards like arsenic and lead. These POU RO units take care of both, providing a greater value to the community than large municipal treatment systems can alone.
Small water systems may have the most at stake when initiating a water treatment plant, as many small systems currently do not treat their water and thus, have the greatest learning curve and operator certification needs ahead of them. Small water systems also must be aware of proposed regulations for several different water contaminants coming and other disinfection rules. POU RO provides a single, cost-efficient way for many water districts to meet the needs of today’s water discoveries – as well as tomorrow’s. Where there may be some additional management oversight to implement the program, in the end real world applications of both programs indicate it provides a significant cost savings for the community.
About the author
Shannon P. Murphy is Vice President of Municipal Water Programs for Watts Premier Inc., a division of Watts Water Technologies, of North Andover, Mass. Murphy holds a Bachelor’s degree in biology from Concordia University in Montreal, Canada and a Master’s degree from Wayne State University in Detroit. Murphy has been a member of the WC&P Technical Review Committee since 2004. He can be reached at [email protected]