Water water everywhere nor any drop to drink! A bit of trivia, that line comes from a poem entitled The Rime of the Ancient Mariner by Samuel Taylor Coleridge published in 1798. Pure water is essential for safe and trouble free cruising. Our experience has been that water is generally available everywhere from a variety of sources. Regardless of the source of the water in our boat tanks, water purification is a necessary practice. Water can be contaminated with a variety of things that can give us an upset stomach or worse! Let’s cover what might be in our water.
- Sediment – this is simply dirt, very fine particles of dirt.
- Chlorine – a blessing and a curse, chlorine or related chemicals called chloramines can come from municipal water systems where it is added as a disinfectant or self-induced as part of our purification practices. I put bleach in my tanks when I get water from a questionable source like a river in Panama. It is best to remove the chlorine before drinking.
- Organic chemical contaminants – these can come from the source water contaminants like pesticides or from chemicals leaching out our tanks and water lines.
- Heavy metals – lead and mercury are at the top of the list. Lead can contaminate water from piping and tank materials. Mercury is everywhere largely coming from environmental contaminants (things like burning batteries in incinerators). Long term exposure to these contaminants is unhealthy; particularly for developing brains.
- Microbes and other creepy crawly things – these are one of the biggest concerns for cruisers. Nothing ruins a day like a good dose of Ecoli sometime in the prior 48 to 72 hours. Ecoli, fecal coliform bacteria, and Cryptosporidium Oocysts are common in water that is found in countries outside the USA.
So, what is the best way to get rid of these contaminants from our water? First of all, we don’t need to eliminate these things from all of our water. From a practical perspective, only the water that we plan to drink directly from the tap needs to be purified. The most practical solution is to have a dedicated tap in the galley for the purified water and then a good filter to purify the water just upstream of the tap.
If you were to Google “water filters” you will find a dizzying list of websites that offer an extensive range of filter options, most target the home consumers. Trolling through a boat show, you will likely find the Seagull system on display. This system has excellent performance and with a relatively small stainless steel filter housing is well designed for a boat. The trade-off for the Seagull’s appealing size is cost. The units are more expensive than standard filter housings. The replacement cartridges for the Seagull system are also more expensive than other standard sized filters.
As an alternative to the Seagull system, it is possible to achieve similar performance with a standard 10″ filter housing and a multi-stage filter cartridge with a pore size <0.5 micron. On our boat we have a system using two standard 10″ housings in series. In the first housing between the tank and a dedicated faucet for the filtered water, we use a standard 5 micron granulated activated carbon (GAC) filter element. This element eliminates excess chlorine, some organics and reduces particulates for the primary filter. The primary filter is a Doulton Ultracarb ceramic filter element. The Doulton Ultracarb filter has multiple stages. The first stage consists of Doulton Ultracarb ceramic which provides genuine sub micron filtration. The cartridge reduces fine particulate matter, bacteria, cysts and turbidity. The pore size of this stage is <0.5 micron. Integrated into this stage is an anti-bacterial matrix containing silver, making the element self-sterilizing and inhibiting bacterial growth in the filter. Stage 2 is an inner core of activated carbon block that removes chlorine, taste, odor and organic compounds. Having this allows the Doulton filter to be used as a single cartridge installation eliminating the need for the pre-filter. Use of the prefilter, however, extends the life of the Doulton filter. Stage 3 is ion exchange resin that reduces Lead and other heavy metals.
Doulton Filter Cartridge Construction
The Seagull company does not provide details of the construction of their filter cartridge. From a comparison of the performance data, it is likely similar to the Doulton Ultracarb in construction.
Both units have comparable performance. What is likely to drive your final purchasing decision is the size of the 2 different units. The system using standard size components is a lower cost alternative but is a larger unit to accommodate on your boat. A cost comparison is provided below.
Either system will be a wise investment and an essential piece of equipment to keep the crew healthy.