This section our site is for those that want to ask questions that are not related to any of our current rainwater tanks.

This is where any questions that don’t fit will be placed and answered in relation to any of our rainwater tanks and additional water saving accessories that you may need when purchasing a rainwater storage tank.

Question:  What Is A First Flush Diverter? Do I Need To Install One?

Answer – A first flush filter is usually fitted to every down pipe that is to feed water to the rainwater tank. The diverter prevents the initial 10-25 litres of water collected from the roof, from entering the inlet of the rainwater tank. Please follow this link to get a complete explanation and video on What Is A First Flush Diverter.

Question: What Size Water Storage Tank Should I Buy?

Answer: This is one of the more often asked questions that I am asked. There is quite a few factors that determine my answer to this.

Is the storage tank to feed water to the home for toilets, washing machines?

How many garden taps are to be connected?

Will the garden taps be feeding an irrigation system?

Will the rainwater harvested be used to keep a swimming pool topped up?

Obviously these questions need to be answered to gauge an idea of the amount of water that will be required to achieve the goals of the customer. We have created a separate page that goes into much more details about what size water tank you need, follow this link to read more.

Question: Do I Need A Water Pump? Or Will Gravity Work?

Answer: This is a question that I get almost on a daily basis and when asked my first question to the customer is always the same:

Is the tank to be connected to the house and service toilets and/or the washing machine?

If the answer is yes, then my response is also yes, a pump will be required for the rainwater tank. The reason being is that when you connect to fixtures in the house, you need a mains backup system. This may be either a manual or automatic system but pressure will be required to operate both types of systems.

Mains backup is obviously required for an installation of this type, as if the water tank is empty, mains water will be required to be diverted to the fixtures, ie – cistern in the toilet.

Now, if the tank is only to be used for filling a pool, or for the garden, gravity may suffice. In saying this the tank to have any real pressure would need to be a minimum of around 3-5m above where the  water is needed.

So if a garden is going to be watered with a hose coming from the tank which is 5m above the tap in the garden the Head of Water may be enough to give adequate pressure. This is rare on most sites and generally I advise customers if they want any pressure at all from the garden tap then a small water pump will be required.

Power usage will be minimal as the pump will only come on when the tap is opened and been used.

In over 90% of cases where people have attempted to use gravity, they tend to call back within 3 months of installation and purchase a pump system. Follow this link to see all of our available pump packages.

Question: What Is A Charged Line?

Answer: Many customers after discussing rainwater tank installations with their builders or plumbers often hear the term “ charged line “ , but are confused what this actually is and how it works.

A charged line is installed when a down-pipe is some distance from the tank it wishes to feed.

For instance their may be a down-pipe coming from the gutter on the opposite side of the house from where the tank is installed. If there is adequate access under the house the plumber doing the tank installation may use a charged line. This would mean fitting a PVC round down-pipe, say 90mm, to the nozzle on the gutter and run it down and then under the house to the tank location, where it would then rise up and into the tank inlet.

As the pipe is PVC and sealed, and as long as the inlet of the tank is at least 750mm lower than the nozzle coming off the gutter, the water will actually fill in the PVC pipe and as water finds its own level will begin to come out the lowest opening which is the opening that is installed over the inlet of the tank.

Of course the pipe will essentially always be charged and hold a certain amount of water. It is only when it is been filled during periods of rain will it then push the water to the lower opening over the tank.

Charged Lines are a very effective way of harvesting large amounts of your roof area, and the more roof are that is harvested, the quicker the tank will be refilled.

We will be constantly updating our water tanks FAQ page with more questions and answers, you are more than welcome to submit your own questions using the form below.

Question: What Do I Need To Construct A Water Tank Base?

Answer: There are few ways that you can install a rainwater tank, so to give you the complete insight into what is right for you we have written a separate page that out lines How To Make A Base For A Rainwater Storage Tank.


  1. I’m glad you mentioned not needing a water pump if using the tank for things such as filling a pool, or for garden use. My wife and I are looking to buy our first home, and one of the homes we really like has a water tank in the backyard. I was just curious as to what they’re for and how to use them. I have a much better idea now!

    • Hi Oscar,

      Thank you for your feedback.

      We’re glad the information was of assistance.

      Kind Regards,

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