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Technical Information Domestic / Rural

Why should you clean my Water Tank/s?

Over time, biological matter enters the tank and begins to decompose. Tank cleaning will reduce potential damage to your Water Pump, assists in the unobstructed flow of water to your Pump, increase the life of your Water Filters, and where there are no Filters, it reduces potential harm to your tap ware...But most importantly, it is the first significant stage in ensuring the purity and health of your drinking water supply.

Why is it that I don’t have a problem with drinking my water, but some visitors and family do?

Our immune systems can grow accustomed to the various water qualities we are exposed to. For example, it is not uncommon for farmers to pass their farms onto their children etc and for generations the same water supply has not caused any noticeable problems; however other people that are used to drinking town-supply water, can be more seriously affected. Your water may even taste, look and smell OK, but the human eye can’t see the bacteria in the water.

As we know, people that are not-well, younger-children and older-people can all have a lower immune system, so it is important to have a “potable” (Drinking) water-supply to your house, that all of your friends and family can enjoy.

Do you have to get inside the tank?

Not normally. In the vast majority of cases we clean the tank without having to get inside. If the tank needs any internal work, we would discuss this with you first.

How do you clean the tank?

We use a high performance semi-trash vacuum pump, and a commercial vacuum head with 50mm lines, to suck the sediment / waste from the bottom of the tank. We are able to adjust the vacuum to remove the waste, whilst losing the least amount of water, to suit each job.

How much water will we lose?

This depends on how much sediment we have to remove; typically we recommend a water tank that collects rain from the roof, to be cleaned every 36 months, if cleaned this regularly, the water loss is minimal.

Tanks that have been left longer will require more water to be used the first time we clean them.

How often do you clean a Water Tank?

This depends on your environment and how much sediment is going to enter your tank. Typically we would recommend every 36 months (3 years) for normal rain collection tank/s.

However in some rural situations, particularly on farms, water can be collected from a river or stream, in this case the volume of sediment can be much higher, and tanks may require cleaning every 12, 18 or 24 months.

We will recommend a maintenance period that suits your specific situation.

When is the best time of year to clean a Water Tank?

Anytime! The process we use allows for minimal water loss. If you’re worried about losing water during summer, just think how much more clean storage your tanks will be able to hold.

Do we have to stop using the water while you do the job?

Yes. When we clean the tank, it is inevitable that we will stir up a small amount of the sediment. We don’t want this being sucked into the water pump, so we need you to turn off the pump and isolate the water supply by turning off the valve at the bottom of the tank or at the pump when we arrive, and leave it off for a minimum of two hours after we have left, for the fine sediment to settle again.

Will the water be safe to drink after you have cleaned the tank?

Cleaning the tank is often the first step in removing the source of bacteria, odour and/or taste issues. However, after a tank is cleaned, you can choose to have the balance of the water in the tank sanitised – this allows for any fine suspended organic matter to be neutralised and taken to the bottom of the tank, it will also kill bacteria and living organisms.

The sanitiser will then self-neutralise after a number of hours, turning into oxygen and water, leaving no chemical residue, taste or odour. The water will be safe to drink 60 minutes after the sanitiser has been applied.

If an existing Ultra Violet system or other bacteria neutralising system is installed, the sanitiser may not be required.

Our operator can advise you what other products or services may be beneficial in your particular circumstance.

What happens to the waste?

The waste is generally made up of biological matter, including windblown dirt and dust, animal faeces, leaves and twigs. We try our best to run our outflow pipe into a garden or paddock where the water can disperse and the waste will breakdown very quickly. We will not direct the waste into a water-way.

How do I keep my water tasting great?

Given our extensive experience, we can independently advise you on the best and most cost effective way to keep your water, pure, safe and tasting great.

What is E.coli?

Escherichia coli (E.coli)

E. coli are common germs (bacteria) normally found in the gut of warm-blooded animals and people.
There are many types of E. coli, most of which are harmless and are an important part of a healthy human intestinal tract. However, some types can cause illness.

One type of disease-causing E. coli is known as Shiga-toxin producing E. coli or STEC. This may also be referred to as Verotoxin E. coli (VTEC).

The types of E. coli that can cause illness can be transmitted through contaminated water or food, or through contact with infected animals or people. It usually takes between 3–9 days after the bacteria are ingested for the first symptoms to appear.

Symptoms of STEC infection:
The symptoms of STEC infection varies for each person but often include:

  • severe stomach cramps
  • mild to severe diarrhoea (which may be bloody)
  • vomiting.

If there is fever, it usually is not very high (less than 38.5˚C).

Most people recover within 5–7 days. Symptoms are generally mild in healthy people, however, they can be severe in children, the elderly, and people with reduced immunity.

Complications of STEC infection:
Around 8–10% of those who are diagnosed with STEC infection develop a potentially life-threatening complication known as hemolytic uremic syndrome (HUS) which affects the kidneys and bloodstream.

How is STEC spread?
Illness due to STEC occurs through:

  • drinking contaminated water
  • eating contaminated raw food
  • drinking unpasteurized (raw) milk
  • contact with infected animals
  • contact with the faeces of infected people.

STEC testing in New Zealand:
In New Zealand screening for STEC is done by community laboratories. Positive cases are confirmed by testing at ESR.
(supplied by the NZ Ministry of Health Oct-2014)

More information:
If you have concerns about someone that is unwell, please call your GP, practice nurse or Healthline 0800 611 116 for free health advice. Healthline is a free 24-hour telephone health information service for all families.

What is Giardia?

Giardia is a food- and water-borne disease that is caused by a parasite found in the gut of infected humans and animals (eg, cattle, sheep, cats, dogs, rats and possums).

How do you get giardia?

You get giardia from:

  • drinking contaminated water or eating contaminated food
  • being in contact with infected animals that are carrying the parasite\
  • being in close contact with someone who has giardia – eg, people living in the same house or if you’re looking after someone who has giardia
  • swallowing water that contains the giardia parasite while you’re swimming or playing in lakes, rivers, springs, ponds, streams and so on.

If you have giardia, you could have:

  • foul smelling diarrhoea
  • stomach cramps and abdominal pain
  • nausea and vomiting
  • weight loss
  • bloating
  • slight fever
  • loss of appetite
  • headache
  • fatigue.

Your symptoms will appear between 3–25 days (but usually between 7–10 days) after you become infected. You can be ill for 3–4 days, and then feel better, then the symptoms may come back.

If you don’t get treatment, this can continue and you can be infectious for months.



If you think you may have giardia, this is what you should do:

Go to your doctor. Take a specimen of some of your faeces (‘poos’) with you in a clean jar, as you’ll need a laboratory test.

If you do have giardia, your doctor will prescribe a medicine such as Flagyl or Dyzole.

While the diarrhoea lasts, drink plenty of water to prevent dehydration. Filtered water or water that has been boiled for one minute is safest.

If you have a child that is ill and they're not drinking, go back to your doctor.

Giardia is a notifiable disease, so before you go back to work (or your child returns to daycare or school) you’ll need to check with your doctor or health protection officer that it’s OK to do so. Usually you’ll be clear when your symptoms have gone.

Here's what you can do to avoid getting giardia – or passing it on.

Avoid drinking water that may be contaminated – don’t drink untreated water from lakes, rivers or streams, or from an area where the water is unsafe because of poor sanitation or where there are no water treatment systems.

If you have to drink water that is taken from a roof, river or lake (eg, in a rural area), it should be boiled for 1 minute or put through an approved filter. The water filter should meet the standard AS/NZS4348:1995.

When swimming in swimming pools, hot pools or spa pools, take care to not swallow the water.

Don’t go swimming in a pool if you have diarrhoea. You need to wait at least 2 weeks after the symptoms have gone – and wash your hands before going for a swim.

Food preparation:
To stop giardia spreading, wash your hands before and after preparing food, after playing or working with animals, and after going to the toilet or changing a baby’s nappy. You need to wash your hands thoroughly with soap and hot water, rinse well and dry them on a clean towel.

Tramping and camping:
Use toilets, when they’re provided.

If there are no toilets, bury your toilet waste and paper at least 50 metres away from water sources, such as rivers and lakes.

Giardia is passed on in the faeces of infected humans and animals. People become infected when they swallow the parasites.
Giardia is common in New Zealand. The parasites can live in the environment for long periods – especially in lakes, rivers, streams and roof water.
(supplied by the NZ Ministry of Health Oct-2014)

More information:
If you have concerns about someone that is unwell, please call your GP, practice nurse or Healthline 0800 611 116 for free health advice. Healthline is a free 24-hour telephone health information service for all families.

What does the NZ Ministry of Health Recommend?

Click on the following link to see the recommendations made by the NZ Ministry of Health regarding Water Tanks used for drinking water. Ministry of Health recommends

What's better, Concrete, Plastic, Steel or Fibreglass for a drinking-water tank?

We often get asked what we type recommend, and why.

After many years of cleaning, repairing and inspecting water tanks, we have noticed some differences; however as I’m not a scientist, I’ve been unable to give a definitive answer.

Let me start by saying that we believe the quality of manufacture in all industries has improved over the years, and we can’t fault one type over another. Typically you will experience an acceptable quality and long-life from either type.

We also have hundreds of customers that have been happy with their own choice of style.

When deciding what style you want, there are many considerations including whether the tank is going to be fully submerged, semi submerged or above ground. Typically any load-bearing situation will probably mean you need to look at a concrete option; however some other tank manufacturers allow some level of submersion which should be discussed with the manufacturers directly.

Our concern is not really with the quality of the tanks, but how easy it is to maintain the quality of the water being stored.

I recently found the following article, written by Kristina & Simon Cope, the owners of a website called www.solarenergyhouse.co.nz in it they discuss their own research and decision making process. I was impressed that they had identified the two main areas of concern we have noticed, being the ph of the stored water and the insulation qualities of the two types.

It is our belief that regular maintenance/cleaning of both styles will significantly reduce any potential issues, along with good filtration systems, however their research was interesting and from what we observe, believe it to be right on target.

Please feel free to visit their site for more information on a variety of building materials and options.

Regards Dave

[Extract written by Kristina & Simon Cope]

Concrete Tanks Make A Significant Impact On Water Quality...

New Zealand rainwater has a low PH on average about 5.4. [ref 1]

This water is acidic. Rainwater is naturally acidic due to the dissolution of carbon dioxide in the atmosphere, forming carbonic acid in the rain. Left in its natural state rain water will remain acidic in the storage tank. (PH below 7 is acidic, PH 7.0 is neutral and PH greater than 7.0 is alkaline).

Storage of rainwater in "Concrete" tanks will raise the PH levels. Surveys have shown that concrete tanks have a median PH 7.5, where other tanks (i.e. PEm, steel and fibreglass) had a median PH of 5.9 [ref 2] The raising of the PH occurs naturally by the alkaline cement particles (containing CaCO3) mixing with the water [ref 3] in the concrete tank.

There are numerous studies undertaken overseas by Doctors and Health professionals that show benefits from higher PH drinking water. Alkaline water which is also referred to as "lonised" water, has shown to improve allergies, skin disease, abdominal complaints and many more ailments. [ref 4]

What Is The Advantages Of Higher 'PH' Water?

A Concrete Tank Provides Greater Insulation...

Concrete tanks that are above ground and more so for those buried provide greater insulation from heat and light and therefore the water temperature is maintained at a more constant temperature. Direct sunlight and increase in water temperature can increase the growth of bacteria and algae in water storage tanks.

Concrete tanks can be either fully or partially buried which increase the aesthetics of the site.

Concrete Tanks Can Be Buried! (aka hidden from sight)

Acidic water may dissolve domestic copper piping and over time could cause pinhole leaks in the plumbing system. [ref 5] Acidic water may also cause leaching of the copper into the water supply and this deposits itself on the bathroom fittings causing a green or grensh blue stain. [ref 6]

Possible Damage to Your Plumbing System & Bathroom Fittings...

Acidic water may dissolve domestic copper piping and over time could cause pinhole leaks in the plumbing system. [ref 5] Acidic water may also cause leaching of the copper into the water supply and this deposits itself on the bathroom fittings causing a green or greenish blue stain. [ref 6]


1 Kingett Mitchell & Associates: Preliminary examination of the nature of urban runoff in New Zealand: August 2001.
2 Kingett Mitchell & Associates: House Roof Runoff: Is it as clean as we think: 2nd South Pacific Stomwater conference 2001
3 Quek, U & Foster (1993): and Thomas & Greene (1993) Rainwater quality from different catchements.
4 Best Water: www.waterionizer.org/Articles & Research
5 Journal AWWA, August 2001, Vol 93m, pp 82-91 and www.toolbase.org.
Macomber, Patricia: Guidelines on Rainwater Catchment Systems.

I want more information:

Please don’t hesitate to ask us for more information; we have a number of documents and experience we can call on, to answer all of your questions. Please contact us to discuss your specific job.

Technical Information - Industrial

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