Why it is so important for you to filter your water

FRIDAY, MARCH 16: After the HWP fire, you may have read or heard the Health Department’s general recommendation that everyone drinking water from a residential water tank should filter their water.

If you’re wondering whether you should follow that advice, the answer is “yes”.  I’ll explain why, but first I want to say that drinking water from residential water tanks still makes sense for Bermuda.  It saves residents money from their not purchasing bottled water, it saves energy by reducing the energy required for processing and shipping bottled water, and it utilizes a resource that is readily available.

However, residents do need to protect themselves from two things: 1) the potential of ingesting coliform and other bacteria that may be at unsafe levels in their tank’s water, and 2) the potential of ingesting contaminants that have collected in their tank’s sediments.  It is this latter risk that I would like to address.

Research conducted by the Bermuda Amphibian Project has shown that pollution has accumulated to toxic levels in pond sediments and is causing adverse effects in wildlife.  The current sources of the most toxic pollutants include vehicle emissions and road run-off. 

As part of our ecological risk assessment, we examined sediments from residential water tanks for the presence of the same pollutants. Our studies showed that water tank sediments can also contain toxic levels of petroleum hydrocarbons from fuel combustion, and heavy metals from vehicles and corrosion.

And, if you live near a roadway, particles of exhaust and road dust are likely settling on your roof and accumulating in your water tank’s sediments.  Furthermore, if you have old metal pipes in your water collection system, you may have even higher levels of metals in your sediments because these pipes have corroded.

This means that even if you live far from a road, there still may be unsafe levels of metals in your tank sediments, as we found in our study.  Researchers from BIOS on behalf of the Department of Environmental Protection have tested a number of water tanks over the past 15 years and found similar results.

So should you worry?  Well, fortunately, these contaminants normally stay bound to the sediments at the bottom of the tank and the water is safe to drink.  But you should filter your water to protect yourself and your family from accidentally ingesting these contaminants. This might occur if the sediments get disturbed, such as after a heavy rain or when water has been added to the tank. 

Ingestion of unsafe amounts of hydrocarbons and metals like lead and mercury, which we found in all tanks, can cause serious health problems.  So it’s much better to decrease your risk and use something like a Brita filter to purify your cooking and drinking water.

Our research has shown that such filters significantly reduce the amount of hydrocarbons and metals in your water just as the product manufacturer states. There are a variety of filtering systems available, from some that filter water at a sink faucet to others that filter all water entering your house from your water tank.

Whichever filter you choose, just be sure it is designed to remove both organic compounds and metals. An additional option is to install a floating foot valve to ensure that water is being removed from the top of the tank’s water column, not the bottom, so there is less chance of sediment being picked up. Of course, you should clean your tank regularly, at least every six years as required by law - the Public Health (Water Storage) Regulations 1951 (amended in 1989) - and your risks will go way down. 

Often, however, when tanks are cleaned the tank sediments are just dumped onto the resident’s property. It is important to recognize that according to Canadian soil quality guidelines, the hydrocarbons and metals in tank sediments can reach levels considered unsafe for residential soils.  Tank sediments should not be distributed in your garden, as is frequently the case, as they could pose a risk to humans, pets or wildlife through accidental ingestion.  These sediments need to be disposed of safely by the tank cleaner, and should definitely not be placed in an area where vegetables will be grown.

Bermuda’s innovative way of catching and storing rain water still provides a valuable source of drinking water. Residents just need to follow the government’s recommendations to ensure their water is fit for consumption: filter your water, making sure to maintain or replace your filter as instructed, clean your tank regularly, and disinfect the water if bacterial levels are too high.  Be aware that sediment filters do not disinfect the water. The Department of Environmental Health can provide information about testing water for bacterial levels and disinfection.

• Dr Jamie Bacon is a Research Associate with the Bermuda Zoological Society and has been the Principal Investigator for the Amphibian Project since 2000.  She is chair of the local environmental group, The Environmental Coalition (ECO), and is vice chair of the global advisory group on the ecotoxicology of amphibians and reptiles to SETAC (the Society of Environmental Toxicology and Chemistry). This work has been funded by the Bermuda Zoological Society, the Departments of Environmental Protection and Conservation Services, Capital G and the Continental Trust Corporation.