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Water Filters

Water FiltersFiltration of private water supplies generally fulfils one or more of three purposes:

  • Removal of sediment, silt, rust and other particulate mater.
  • Pre-filtration: removal of waterborne cysts and cryptosporidium. Colloidal very fine silt and clay; this is one micron filtration
  • Purification, i.e. the removal of pesticides and other organic chemicals, taste, odour and chlorine; this is carbon purification.

All these functions are available in the form of cartridge filters which fit into wall mounted housings straight after the pump.

I would suggest the minimum filtration for any home water supply is one w 10j polyspun 1 micron. This is installed straight after the pump and before the water enters the house.

My first concern is with getting the water from the roof to the tanks as clean as possible. The first step would be gutter whiskers or if trees are overhead or nearby, consider leaf guard: this is a plastic mesh that clips over the spouting. This sheds leaf and birds from the spouting leading to cleaner tank water. Then extoption might be first flush diverters. These are mounted on the downpipes or somewhere before the tank. They let the first lot of rain wash the roof to waste then divert the clean water to the tank.

Rain Heads – another option

These units fit on the downpipes, are easily installed and are very effective. They have a leaf slide to divert debris off the screen. A mosquito proof stainless steel screen with 0.955 mm, minimal maintenance required.

The last thing to do before the pump gets the water is a floating suction. Any debris that gets past any of these measures will finish up on the bottom of the tank where the pump suction normally is.

With a floating suction the pump inlet is just below the surface by a float and is only getting clean water. You don’t have to use all of these options. But if you were to contact me I could talk to you about the best options for your situation.
We now have clean water in the tank. We should talk about filtration after the pump and before you drink it.

Drinking Water Standards For New Zealand 2000

As adopted by the Ministry of Health list, Drinking Water Standards 200 outlines the maximum concentrations of chemical and microbiological contaminants acceptable for public health in drinking water. There are usually three different sources of water used in rural areas, either alone or in combination. There are common problems associated with each and other problems specific to the type of source.
The Main Sources are:

  • Rain water
  • Surface water
  • Ground water

In all cases the main requirement is that the water be micro-biologically safe to drink, or in other words, free from pathogenic (disease causing) organisms. The standard bacteria test in water is for E.coli, A positive result indicates faecal contamination of water. No E.coli should be detected in any 100 ml water sample. Under the drinking water standards NZ, if any E.coli is present, the water is unacceptable.

For the purpose of this presentation I will just talk about rain water as about 90% of the household water I deal with is roof water.

Rain Water

Typical source of drinking water supply is the collection and storage of rain water from the roof delivered to use via a pressure pump. The quality of this in terms of mineral/chemical contaminants is usually very good. However, it is almost always contaminated with micro-organisms.

Faecal matter due to birds, possums, cats, mice etc. on exposed roofs. Anybody that is on tank water will be well aware of just how much dirt and dust and general organic matter such as leaves and moss can collect on the roof and in the guttering. If you are like most of us and only clean out the guttering once a year then you will know about the hands full of putrid decaying matter that can build up. This produces a very nutrient rich broth that encourages bacterial growth in storage tanks.

Now What Can We Do About This?

This is where filtration comes in.
On most house installations you should have a strainer before the pump. After the pump there are a lot of options; I would mostly go with a whole house cartridge system. This means all the water that enters your house is treated, and safe.

You should have two cartridge housings, one would have a poly pleated cartridge say 20 micron. This removes larger partials and is washable, so reusable. The other would be a polyspun cartridge; this is not to be reused. It is usual to change this at 6 or 12 month intervals. The PS cartridge removes cysts, rust, dirt and to some extent giardia. If you opt for an under bench filter with one tap at the sink, you should be aware that when you clean your teeth in the bathroom the water is not safe.

If taste or smell is an issue a third housing could be added with a carbon filter, but I would be looking for the cause of the smell first. Well that’s your crash course on filters, you don’t have to do all of these things, but talk to me about it and I will come up with a solution to suit your needs.

Ulta-Violet Sterilisers

After all the cartridge filtration is in place and you still have some money left. You might consider this. It is installed straight after the filters and kills cysts, cryptosporidium left in faecal matter from birds and animals. This system is used in schools and kindergartens, and households anywhere where that public health is a concern. Talk to me about this; it’s probably not as expensive as you think.

Call me about any problems or queries you have. I will be happy to call on you to advise and quote on any pump or filter system you are considering.