EPA New England Press Releases

MWRA FILTRATION: POINT - COUNTERPOINT

MWRA says filtration isn't needed. It says other steps it is taking to protect the Wachusett Reservoir water supply will solve health problems.

Filtering the Wachusett -- the source of drinking water for more than 2 million people -- is a fundamental issue of public health. The best protection against waterborne disease is the widely- accepted multi-barrier approach that includes watershed protection, disinfection, delivery-pipe maintenance -- and filtration. All four play critical roles in the multiple barrier. To bypass any one piece, as MWRA proposes with filtration, is to remove a cornerstone of the multiple barrier.

But MWRA says it can meet safe drinking water regulations without filtration.

MWRA water failed to meet the requirements for avoiding filtration by the federal deadline of December 1991. It continues to fail to meet current state and federal safe drinking water requirements. And without filtration, it is extremely unlikely MWRA will be able to meet federal water supply standards in the future.

MWRA's own data point the other way:

• Systemwide, 10 monthly total coliform rule violations have been reported since 1995. Fourteen MWRA communities in Greater Boston have violated the coliform rule since 1995. Elevated coliform levels have also been reported at the Commonwealth Avenue pumping station where MWRA water enters Greater Boston's distribution system.
  
  
• Giardia and cryptosporidum, two common waterborne pathogens, have been found in MWRA water samples. While chlorination can kill Giardia, it does not kill cryptosporidium. Filtration, however, removes both.
  
  

Then why haven't there been any serious outbreaks of waterborne disease within the MWRA system? Does this mean the water IS safe to drink?

Experts believe that waterborne illness is generally under- reported, partly because many people don't link their gastro- intestinal illnesses to their drinking water and in part because small outbreaks are not likely to be detected by current disease surveillance systems.

There's also plain good fortune. As a 1992 MWRA paper noted: "The fact that there are no documented waterborne disease outbreaks associated with the MWRA system may be due to luck, to the difficulty of documenting the source of such disease outbreaks or to the short period of time for which reported data on such disease is available."

But MWRA says its plans to increase disinfection, along with its watershed protection and other efforts, will resolve such problems.

First of all, even if MWRA water sampling has shown some improvement, the fact remains that the water is out of compliance with current regulations designed to assure public health.

Increasing disinfection by using more chlorine will have some beneficial results. But chlorine disinfection is limited. It does not, for example, kill cryptosporidium, but filtration does remove it.

Studies have also linked higher levels of chlorine disinfection by-products (DBPs), such as trihalomethanes, to cancer. Under its current plans, MWRA may not meet new federal DBP limits that will be finalized in the next year.

As MWRA Executive Director Douglas MacDonald said in a Sept. 9, 1997 letter, to Weston town officials, "Although cancer risks from disinfection by-products are generally thought to be very low in relation to the benefits of disinfection, an opportunity to minimize disinfection by-products is an important water treatment objective."

Filtration is an effective, affordable way to meet that objective.

MWRA says it meets current DBP limits for trihalomethanes (THMs). As for future DBP limits, there's no reason to worry about standards that haven't yet been set and are uncertain.

MWRA's compliance with current THM limits is due to the low levels of chlorine MWRA has been using. MWRA's plans to significantly increase chlorination mean it will approach current limits and may well exceed stricter THM limits, the first set of which becomes law in November 1998. That new level sets THM limits 20 percent lower than the current standard. Apart from regulations, the fact is that higher DBP levels mean higher risks. Filtration allows less chlorine and less risk.

MWRA also argues that its data show that cryptosporidum is not the problem you say it is, that its cryptosporidium levels are below levels that should worry the public. It also says it has solved its coliform violation problems at the Wachusett and that elevated coliform levels at the Commonwealth Avenue Pump Station reflect a problem with the sampling station, not the water.

• Regarding cryptosporidium:
  
  In fact, no formal regulations currently set cryptosporidium limits. But scientific research has found that even very low levels of cryptosporidium can cause illness, including severe gastro-intestinal outbreaks. And cryptosporidium has been found in water samples from the Wachusett and its tributaries.
  
  
• Regarding coliform:
  
  Coliform levels are down at the Wachusett intake, but streams feeding the Wachusett show very high coliform spikes. To depend on "dilution as a solution" is an unproven, risky answer to this coliform presence.

As for the Commonwealth Avenue pump station, MWRA has only speculated that the coliform problems are due to the sampling station. At present, the facts are that numerous samples at the Commonwealth pump station and in communities throughout the MWRA system show excessive levels of total coliform bacteria.

There is obviously disagreement over these technical issues. That's why it would make sense for MWRA to complete more studies to make sure this expensive action is meeting real problems, not just some bureaucratic schedule.

First, no one disagrees with the baseline reality that MWRA failed to meet filtration avoidance criteria by the federal deadline. And it remains obvious that MWRA will not meet those criteria by 1998.

Studies are fine, but they are no substitute for action, especially action involving something as basic to public health as ensuring safe drinking water.

That's why EPA simply wants MWRA to comply with federal law and to join the national mainstream: Virtually every major surface water supply system in the country has accepted filtration as an affordable and effective part of the multiple barrier. Of 235 systems serving populations of 100,000 people, for example, only seven have not been required to filter. And each of those had far less developed watersheds than the Wachusett watershed can ever be.

But MWRA says a panel of independent experts it convened to review the situation supported MWRA's current plan of filtration avoidance.

EPA staff who attended panel meetings believe that statement mischaracterizes the experts' conclusions.

First of all, no formal vote was ever taken nor was any sort of consensus position asked for or developed. Indeed, members of the expert panel have told EPA that, in fact, MWRA DOES need filtration. MWRA should increase currently inadequate disinfection practices, these panel members tell EPA, but filtration is also needed because of cancer risks tied to relying too heavily on increased chlorination over the long term.

But MWRA says it's not just chlorination, but other steps, such as covering the Norumbega Reservoir and watershed protection, that will enable it to achieve the same public health goals as filtration.

EPA enthusiastically supports MWRA's land acquisition and other watershed protection efforts. Indeed, EPA wants MWRA and MDC to keep to their own schedule for watershed protection and continue these practices.

EPA also believes that covering the Norumbega Reservoir is an important part of meeting public health goals. But as MWRA has previously agreed, none of these actions is mutually exclusive, or a substitute for filtration. Rather than supplanting such measures, filtration complements them. And filtration achieves some benefits, such as greatly reducing cryptosporidium and disinfection byproducts (DBPs), that other methods alone fail to accomplish.

Wouldn't focusing on improving the local distribution system pipes give us safer water faster than building a filtration plant? And what's the point of spending all this money on filtration and other steps if it means clean water still ends up in dirty local pipes?

Local distribution systems should be cleaned up. EPA commends MWRA for helping its member communities do so. But the overall process will take 20 years and $1 billion to complete. And it certainly makes no sense to introduce dirty water into local pipes at ANY time, especially after they have been upgraded.

Has EPA taken a step like this anywhere else?

Fortunately, the vast majority of water systems have complied with filtration requirements. Of the 235 water systems in America serving populations of more than 100,000, 224 systems - or 95 percent - have filtration. MWRA is an exception to the rule. And EPA is forced to act in part because of MWRA's pattern of delay. In 1992, the Massachusetts DEP determined that the MWRA needed to filter at the Wachusett. Over a year later, as part of a state consent order, MWRA agreed to have filtration in place by 2001. Then, last summer, it pushed that back two years, to 2003. Now MWRA wants even more time, saying it wants more study before constructing the filtration system they are legally obligated to install. Further study is no substitute for legally-required corrective action on such a basic public health problem.

Would ozonation alone -- i.e., without filtration -- be an adequate response to MWRA's water problems?

No. While ozonation can help inactivate cryptosporidium, its use alone creates a by-product that in turn feeds bacteria in the local distribution system pipes. Such bacteria create an additional health risk. Filtration could mitigate that by-product threat from ozonation.