Domestic water treatment systems

Actually, when it comes to the water supply, Canadians are quite fortunate, as we find within our borders a sizeable fraction of the world’s fresh water supply. Which doesn’t mean that it’s infinite or that it should be taken for granted. Practically all water sources are subject to greater or lesser degrees of contamination by natural or man-made pollutants. Some, like iron and sulphur, are quite benign and fall more into the category of irritants that, if present in high concentrations, must be removed to soften the water or make it more acceptable for human use and consumption. But others, like heavy metals, certain man-made chemicals and organic pollutants must be removed, as they can pose grave short and long term health risks.
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Types
Characteristics
Installation
Miscellaneous
Maintenance
Accessories
Large cities and towns treat their own water supplies. This treatment, primarily chlorination, targets organic pollutants like pathogenic bacteria, viruses and parasites. This water is constantly monitored and is usually safe although, in certain areas, boiled water advisories are a fact of life and many people are compelled to solve the problem by buying the water they consume, an expensive and short term alternative when compared to the cost of a good domestic water treatment system.

The water from surface and artesian wells is another matter. Again, although generally safe, water from ground sources must be regularly monitored, as although a well may have been in operation for many years, outside conditions affecting the water quality can vary. Residential development, agricultural run-off and certain types of industry in the area can, over time, contaminate ground water. Although environmental regulations and monitoring have helped contain the problem, keep in mind that your water may have travelled underground for miles before landing in your well and you can never be sure of what it has picked up on the way. If your drinking water source is a river, a stream, a lake or a well there’s no choice, it must be disinfected.

Types

In the main, there are different treatment options on the market, each designed to treat a specific, or set, of problems:

Pour-through filters

The most common and inexpensive filtration system, pour-through filters are simple units that operate like drip coffee makers, as they use faucet water poured directly through a removable, activated charcoal filter and into a pitcher. The pitcher can hold a quart or two and the filter removes larger sediment, lead and some objectionable tastes like chlorine. Low capacity, used only for filtering treated drinking water.

Ceramic cartridges

Ceramic cartridge walls measure between 1 and 2 centimetres and are studded with microscopic (see “microns” below) pores that trap sediment, bacterial and parasitic pathogens, but not chemical contaminants or viruses. Their small pore size makes them unsuitable for large-volume water purification and they must be cleaned regularly. Cartridge performance is enhanced by activated charcoal cores that remove odours, tastes and chlorine, although the core efficiency will degrade slightly over time.

Ultraviolet (UV)

Ultraviolet light units kill living organisms such as bacteria, viruses, mushrooms, spores, algae and parasites. They have no effect on inorganic pollutants like sediment, chemicals and metals. To alleviate this problem, they can be coupled with a particle filtration system such as sediment and/or activated charcoal filters to remove organic chemicals, silt, sand, etc. UV systems are particularly useful in households that get their water from artesian or surface wells, rivers or lakes. They come in models rated for 2 to 3 persons, 3 to 5 persons, 5 or more persons, etc.

Reverse osmosis

In the reverse osmosis process, water is forced through a fine-pored, semi-permeable membrane to remove minerals, heavy metals, nitrates, fluorides, pesticides and chlorine. Although relatively inexpensive, it’s considered to be slow, requiring one hour to produce one gallon; wasteful, as it needs three to four gallons of untreated water to produce one gallon of clean liquid, and isn’t recommended for use with untreated water. It can be coupled with other filtration systems to remove larger sediment particles.

Ozone

These devices emit small quantities of ozone gas that’s produced by drawing air between two highly charged electrodes. The gas from this process destroys pathogens and oxidizes organic matter, but has no effect on water taste and smell. Although available in small-scale units for designed domestic use, ozone purification is rarely used in homes, finding instead more widespread applications in municipal wastewater treatment and in industrial applications like food production and in the paper and textile industries.

Activated charcoal

Since it’s very effective in absorbing and neutralizing organic chemicals, activated charcoal, a.k.a. activated carbon, is widely used to remove odours, bad tastes, pesticides and chlorine in water. It’s produced by heating wood, coconut shells, etc, at high temperatures in a controlled amount of air. Although it renders water palatable, it’s not a good solution when it comes to ridding water of organic hazards such as bacteria, viruses, etc. As well, it won’t remove hardness, sodium and fluoride. Domestic activated charcoal filters come in pour-through, faucet mounted and high-volume models that can be installed under the sink. After pour-through filters, faucet-mounted activated charcoal types are the most widely used systems.

Sediment filters

Sediment filters remove coarse and fine sand, calcium, algae, rust and silt. Mostly found in under-the-sink and centrally located systems, they’re the first in line in multiple cartridge filtration systems ahead of ceramic, UV and activated charcoal units. Sediment filters are the least expensive to replace.

Water softeners

Water that’s heavily mineralized is said to be hard. This “hardness” is caused by calcium and/or magnesium that, over time, results in clogged pipes and the build-up of scale in water heaters and teakettles and, as scale is a poor heat conductor, accompanied by the loss of efficiency of these units. Left untreated, pipes and water heaters can become clogged or damaged beyond repair and must be replaced. As well, soaps and detergents don’t mix well in hard water, don’t produce much lather and thus, larger and larger quantities are needed to wash clothes, dishes and… ourselves.

Although there are filtration systems that can handle the job, they require that all the water in the house be filtered. The cost for this can be prohibitive and there’s a less expensive alternative. Water softeners use plastic, sodium covered beads called zeolite (zéolite en francais) to filter water and remove the bothersome minerals. The sodium ions in the zeolite that don’t precipitate, replace the natural occurring calcium and magnesium ions that do. When the zeolite becomes saturated with calcium and magnesium ions, the water softener produces brine to strip the zeolite of these ions that are replaced by new sodium ions and the softening cycle starts again.

Characteristics

    Water testing
    So your water tastes and smells bad and you’re at a loss to explain why. You have also noticed that the clothes come out of the washer filled with white streaks from undissolved detergent. The short answer to these problems may be hard, or mineralized, water.

    Or again, you may have noticed that the kids seem to suffer from frequent bouts of gastroenteritis or diarrhoea. Of course it may be from exposure at school or the playground, or maybe not… If you harbour doubts don’t wait, rush a water sample to a reputable, accredited laboratory. There are specialized tests to detect mineral, metal and bacterial levels. These test results are compared to government established minimum safe levels and from these comparisons you’ll know whether or not you have a problem.

    Note that our stores carry an inexpensive and reliable home bacteria test kit.
    Choosing a system
    There are various systems on the market designed to deal with different complaints, so to choose the right system, you must first identify the undesirable substances that need to be eliminated.

    Certain problems associated with odour and taste can be corrected quite simply with a basic, off-the-shelf purification system, but when the problem poses a potential health risk, it’s time to bring in a qualified specialist. This person will analyze the problem and propose a system that fits the situation.

    From this information, you’ll be able to select a single or multiple filter system that will remove or kill all the undesirable elements that are sources of water contamination in your home.

Installation

The systems are usually connected to the cold water line in the kitchen and hidden from view in the cupboard under the sink or centrally located ahead of the main valve to filter all of the water used in the house. They can be installed by a homeowner possessing a minimum of tools and expertise. The following tools should be sufficient to tackle most jobs:
  • Pipe cutter or hacksaw
  • Tape measure
  • Wrenches
  • Plumber’s tape
  • Screwdriver
  • Drill and bits

As plastic pipe and pressure fittings are now included with most home filtration systems, soldering copper pipes shouldn’t be a necessity. In this vein, a truly ingenious accessory is the self-piercing valve that does away with the need to cut copper pipe with a pipe cutter or hacksaw. These units are designed to clamp around the pipe and, when tightened, pierce the pipe and automatically create their own seals.
    More on activated charcoal
    Lead and other heavy metals can only be removed by a very specific type of activated charcoal filter. Unless the manufacturer indicates that its product will remove heavy metals, the consumer should assume that the activated charcoal filter is incapable of doing so.

    Activated charcoal filters need to be changed periodically as they become clogged over time. Usually, manufacturers will indicate the useful lifespan on their packaging or instruction sheets. Water taste and colour is another indication that the filter is no longer effectively fulfilling its purpose. To prolong the activated charcoal filter’s lifespan, it’s a good idea to install a less expensive sediment filter on the feeder line ahead of the charcoal filter.

    Regularly changing the activated charcoal filter becomes even more important when you consider that if not changed regularly, and based on the manufacturer’s recommendations, this type of filter can become a breeding ground for harmful pathogens. In fact, some bacteria feed on the very material that the filter is designed to block.

Miscellaneous

  • A micron is a unit of measurement, 1/1,000,000 of a meter (or 1/25,000 of an inch) that, in this case, is used to designate filter pore size. Ranging from ½ to 200, the most common pore size used in water filters is 5 microns. Unless you like to spend money needlessly, make sure that the pore size matches the job. A 1-micron filter will become clogged more quickly than a 50-micron filter that will let larger particles go through.

  • There’s a line of filters specifically designed for refrigerator ice-makers.

  • Reverse osmosis systems must be in constant operation, otherwise the filtration membrane will dry and a crust of minerals and other matter will clog the membrane and reduce its effectiveness.

  • Did you know that silver is very effective in killing bacteria and some ceramic filter models are impregnated with a thin layer? In fact, it’s no accident that silver became the metal of choice in cutlery and dishware (for those who could afford it). Keep this in mind when comparing pathogen purification systems.

  • There may be occasions when you don’t need to filter your water, filling the backyard pool, watering the grass, pressure-washing the vinyl siding or washing the car to name a few. With these activities in mind, manufacturers of central filtration systems have added bypass valves on some units. In most cases, a simple flick of a switch directs the water away from the filtration cartridges and directly into the home system. Of course, this feature applies solely to central systems that filter all of the water coming into the house. If you do employ this device, remember that unfiltered water has now been introduced into the piping system throughout the house. This won’t create a big problem as long as your water is not being treated to remove harmful pathogens. On the other hand, if pathogens are present, the addition of a central UV or under-the-sink, silver impregnated ceramic cartridge will solve the problem.

  • Power outages can be significant events for those who use a UV system to kill pathogens, as UV systems need electricity to operate. When this happens, the UV unit shuts down and a small quantity of contaminated water can find its way into the system via the pressure tank, even though the water pump has also been neutralized. One way to prevent contaminated water from entering the system is to install a solenoid cut-off valve on the main water line to block water flow the instant the power goes off. However, if you do suspect that untreated water has made its way into the system, a full system purge is in order, a practice that should be performed every year in any event. The other power outage related problem to watch for is damage to the delicate ballasts that control the UV lamp. These ballasts can be damaged when the power comes back on and “surges” through the line. To prevent damage, install your UV unit on a dedicated electrical circuit and protect this circuit with a surge protector like the one you use on your home computer.

Maintenance

Maintenance consists of replacement and/or cleaning sediment and ceramic filters. Activated charcoal filters cannot be cleaned and hence, must be replaced. For UV systems, the lamp should be replaced no less than once per year or when the built-in sound alarm goes off indicating a lamp burnout.

Accessories

The replaceable cartridge filters are the heart of the system and, once installed, should be the only accessories you’ll need:
*Please note that the above is a list of the most common complaints.
*ComplaintCeramicActivated charcoalPour-throughSediment
Coarse sandYesYesYesYes
Calcium -Yes -No
AlgaeYes - -Yes
Rust - - -Yes
Coarse sedimentYesYes -Yes
Fine sedimentYesYes -Yes
OdoursYesYesYes -
Bad tastesYesYesYes -
ChlorineYesYesYes -
Volatile organics -Yes - -
Lead -Some - -
Pesticides -Yes - -
Coliform bacteriaYesNo - -
Fecal coliformYesNo - -
SporesYesNo - -
MushroomsYesNo - -
In the light of recent tragic events related to water safety, you owe it to yourself and your family to make sure that your home drinking water is beyond reproach. As well, although many undesirable substances may not pose health risks, they can give off bad odours and tastes that will surely spoil your morning coffee… every morning.
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