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Our Q&A about collecting water and using water tanks safely

At Happy Tanks, your Auckland and Northland water tank cleaning and repair specialists, we want you to get the most out of your water tank and make sure your water is pure, safe and tastes great, that’s why we are happy to provide water tank advice. If you have any questions about cleaning, maintenance or repairs of water tanks, feel free to contact us or read the commonly asked questions and answers below. It may have the information you are looking for.

Over time, biological matter enters the tank and begins to decompose. It is the first stage ensuring the purity and health of your drinking water supply. Tank cleaning will reduce potential damage to your water pump and increases the life of your water filters. Where there are no filters, it also reduces potential harm to your appliances that use water.

In most cases we can clean the tank and sanitise the water without having to get inside. If the tank needs any internal work, we will discuss this with you first.

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 can adjust the vacuum to remove the waste, whilst losing the least amount of water, to suit each job.

This all depends on how much sediment we must remove and how water is currently in the tank. Generally, we can vacuum clean a tank while only losing 10-25% if the tank is full.

This depends on your environment and how much sediment is going to enter your tank. Typically, we would recommend every 3-5 years for normal rain collection tank/s. However, in some situations where tree matter is abundant in guttering, water is pumped into the tank from another source or if the water sits stagnant for long periods of time it may require cleaning for frequently. We will recommend a maintenance period that suits your specific situation.

Anytime! The vacuum process we use allows for minimal water loss. But the more water you have in your tank, the more efficient the clean will be.

The water tank we are cleaning must be isolated from the water pump or the pump must be switched off during the cleaning. This is so any sediment inadvertently stirred up does not get sucked into your pump. We ask for the tank to remain isolated for a minimum of 90mins after the clean has been completed.

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 remainder 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 is hydrogen peroxide based and is 99% active for 60mins, turning into oxygen, leaving no chemical residue, taste or odour. The water will be safe to drink 90 minutes after the sanitiser has been applied.

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

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.

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.

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.

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.

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.

If you have any questions or require water tank advice, please contact us.