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Water Supply (page 3)...

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Water Purification

Initial Filtration

So now you have water laid on to your cottage. How do you ensure it's safe to drink? This is where filtering and purification come into play. If you have any form of particulate matter clouding your water, or if your water tank sometimes taints your water with rust (older tanks will do this when they are first used following a period of non-use), then you may need a particulate filter on the main cold water output pipe from your water tank, ahead of your purification system. A typical one is the Rainfresh Whole House or Under Sink Water Filter (available at Canadian Tire), for which filter cartridges of various pore sizes can be purchased, allowing you to tailor the extent of the initial filtration depending upon your own needs. There are many filter manufacturers, as you will find out when you do an internet search, and you should do your own research on this.

Obtaining Potable Water

There are six basic means of reducing the contaminants in water, but not all of them produce potable (safe, drinkable) water. Also, what one person considers safe may be different from another person's point of view, depending on which contaminants they consider to be less harmful. The methods are:

Ceramic/Carbon Filters

There are many filters on the market, and, again, it is necessary to research them carefully. Simple activated charcoal filters such as those used in the Brita products only improve the taste of water by removing chlorine, some heavy metals, fine solid particles and some hardness. They are not designed to filter out bacteria and viruses. For a more effective purification system, you should look at combination ceramic/carbon filters that have fine pore sizes to filter out the contaminants that the activated charcoal can't handle, such as bacteria, protozoa and parasites such as giardia. The different makes of filters will have different characteristics and efficiencies in removing common impurities. Throughput of most of these filters is low, and they can only be used to provide limited quantities of drinking water; they are not suitable for whole-house filtering. Hence, they usually come as counter-top or under-the-counter units for the kitchen or bathroom. In all cases, filter cartridges have to be replaced regularly.

For comparisons of the cost and performance of various water filters, click here. Whatever you do, read the claims each company makes for its products, and (if possible) obtain third-party verification. It's a jungle out there!

We use a reasonably-priced ceramic/charcoal system from Rainfresh that removes 100% of faecal and coliform bacteria, as well as any harmful cysts such as giardia. From our point of view, it removes the stuff that will make you ill in short order.

Reverse Osmosis Systems

This is a method of forcing water under pressure through a semi-permeable membrane to remove impurities. There are two disadvantages to this process. First, by itself it does not remove all bacteria and viruses, and second, it is wasteful of water, because at least half the water volume is lost as it accumulates the contaminants and is flushed away. It is, however, good at removing chemical and heavy metal contaminants.

Reverse Osmosis is often used in conjunction with other types of filters such as ceramic/carbon to achieve a high degree of purification. There are, however, complaints that the water has a flat taste. It is also one of the more expensive options.

Ion Exchange Units

These are primarily used for softening water by removing calcium and magnesium ions that can cause scale build-up in plumbing and appliances. This process does not remove bacteria and many other organic or inorganic components, and so should be used in conjunction with other methods. Hard water in itself is not a health risk (in fact, it may even be a health benefit), but it does reduce the effectiveness of cleaning agents.


Distillation is a process whereby water is boiled and the steam is condensed into a separate container, and it is very good at removing virtually all impurities and contaminants. However, it is expensive, as it requires large amounts of energy to heat the water, and the resultant condensate tastes flat and uninteresting.

Ultra-Violet (UV) Treatment

This uses a UV light source enclosed in a protective transparent sleeve to disinfect water. The UV energy is absorbed by the reproductive systems of bacteria and viruses, and makes them unable to reproduce, thus eliminating the risk of disease. It does not, however, have any effect upon chemical contaminants and heavy metals. It also requires that the water be very clear when passing through the UV chamber, so pre-filtering to remove particulate matter may be necessary. It may also be used in conjunction with other methods that will remove chemicals and heavy metals. Because their throughput is high, U/V systems can be used to treat the entire water supply for the house or cottage.

For more information on these UV systems, see the page here about the one we have installed.

UV purification systems generally use a fluorescent tube as the source of the UV rays. Replacement of this tube costs in excess of $100. A new technology on the market is a small-scale LED UV purification system available from Acuva Technologies in Vancouver. It is designed for under-the-sink use in cottages, RV's and boats, and produces a litre of purified water per minute using a LED 12 volt DC UV source. At present (June, 2016), this system costs an unbelievable $2,400, so it is out of the reach of most of us. However, the technology is worth watching, as it will get much cheaper over time, and additional products may come out of this company in future. It would be nice to see replacement LED bulbs for whole-house systems (that currently use fluorescent UV bulbs), and flow sensors that will turn on the UV system only when the water is flowing out of the taps. The use of LEDs should significantly reduce the power requirements of these systems.


Ozonators are not common in North America, and most of the products on the market are designed for small-scale use, and not whole-house water purification. There is also a lot of medicine-show-type hype about the use of ozone and its beneficial effects that I would treat with a deal of scepticism. However, ozonator equipment is available, but is generally expensive. It is effective in killing bacteria, but requires post-filtration to remove insoluble oxidized minerals such as iron, manganese and suplhur. Here is an informative (though not very well-written) article from Wilkes University on ozonation.

Which purification system should you use?

Of the methods described above, only distillation removes nearly all the contaminants. However, because of the cost, you will likely want to consider cheaper alternatives. Ceramic/carbon filters and UV systems will remove harmful bacteria and viruses as well as some chemicals and heavy metals, thus eliminating the chances of immediate illness. A lot depends on your own particular situation as to which system or systems to choose. If you get a sample of your water tested by a commercial lab service, they will be able to tell you which organic and inorganic contaminants occur in it, and their concentrations. Once you have this information in hand, you will find it easier to make a decision on the approach you need to take.

Click here for a general article on water purification in Wikipedia, here for an article at, and here for an article at

Disinfecting your well

Sometimes it is possible to ensure that your water supply is potable by ensuring that no surface water can enter the well and bring contaminants with it. To do this, the top of the well should be extended at least 30cm (12ins) above ground level, and the ground surface should slope away from the well. Ideally, the well casing should be surrounded by an outward-sloping concrete slab that extends 0.6 metres (2ft) from the well casing. The well casing itself should be sealed for a depth of at least 3 metres (10ft) using tight fine-grained clay, bentonite or cement grout. The top of the well should be sealed to prevent any entry of water, and may have an air vent pipe that turns downward and is covered with a fine screen. Before the well water can be considered to be safe, it should be disinfected. Guidelines for the procedure to follow and the volume of chlorine to use are given at these two links:

Health Canada
Ministry of Environment, British Columbia

An important aspect of these instructions is that you must ensure that very little of the chlorine gets into the septic system, otherwise it will kill the bacteria that break down the sewage. When flushing the chlorine out of the well, use an outside tap to run the chlorinated water into an area where it will not harm plants, and will not drain into fish-bearing bodies of water. Disinfection may be necessary not only on new wells, but on wells that have been repaired in some way. After disinfection, and before drinking the water, you should have the water tested two or three times over several weeks, as indicated in the guidelines given at the links above. The Province of Ontario offers free testing for bacterial contamination to Ontario homeowners through public health offices.

Water Heaters

Water heaters come in a variety of sizes, with 40 to 60 gallons (189 to 280 litres) being the norm for most homes. You will need this size if you have more than one bathroom, a dishwasher and a washing machine. Otherwise, if your hot water needs are modest, you can make do with a 25 gallon (114 litres) heater.

The larger electric heaters have two heating elements (top and bottom of the tank) and require a 240-volt power service, but some of the smaller heaters have a single heating element (at the bottom of the tank), and can run on a standard 120-volt service.

Varieties of propane water heaters are also available, including tankless heaters. Propane is an option you may consider if you have a propane furnace too. Personally, I would go with the tank-type heaters, as my experience with the tankless variety in England is that their throughput and heat output is inadequate for having a shower. It may just be that British plumbing is generally inadequate, and having grown up in England and visited there frequently, my opinion remains the same. The tankless variety does, however, have some benefits. They can be mounted on a wall, and their exhaust gases can be routed through a duct in the wall, without the need for a chimney. I suspect that they may also be easier to winterize, but don't quote me on this.

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© 2009 - 2019, David Mallinson. --- Last updated 17-Oct-2019