How to use a rainwater tank to water garden?

Hello Everyone,

I currently have a 1000L rainwater tank in the back garden, which is only used to supply one toilet using an automatic outdoor pump.

This seems a bit of a waste. My plan would be to somehow use this pump to also supply this rainwater to the front of the house (where there is currently no water supply) to water the garden/wash the car.

As can hopefully be seen from the attached diagram, my plan is to Tee off the pump outlet, run a pipe under a patio (trench and protect with sand), through a garden bed and probably use a Tap Post so I can use a hose. Distance is approx. 50 meters round the side of the house.

I would also like the option to possibly use this pipe to install Drip Irrigation along the pipe at the garden bed. This would, naturally, only water the garden when the pump is activated. I could either manually run the pump to water the garden or simply allow it to happen as a side effect of using the toilet or front-of-house hose.

So my questions are as follows:

1. Would it be possible to use standard Poly Pipe? Or could I use a 'standard' garden hose?
2. Would there be water pressure issues? The system would be 'closed' so I don't think so.
3. What have I missed?!

Many Thanks in advance.

Find more posts tagged with

Gardening

Plumbing

Comments

MitchellMc

Welcome to the Bunnings Workshop community @NotHarryPotter. It's wonderful to have you join us, and many thanks for your question about plumbing a garden tap.

Having the tap connected sounds entirely possible. First, you'll need to check with your local council to find out whether a registered plumber is required for this work.

You'll need to determine whether the current pump is designed to cope with your needs and additional connection. If its only purpose was to fill the toilet periodically, it might not be capable of providing the flow required to use as a garden tap to water your yard.

Due to the drip irrigation, the system will be open and constantly lose pressure. I would have thought this would cause the pressure switch to activate and the pump to turn on and off constantly. I believe these pumps work as when the pressure drops in the line, they switch on and then turn off when they receive back pressure. For instance, let's say that the pump switches on below 95psi and off at 100psi. It will build pressure in the line to 100psi and turn off. Since the drippers release a slow flow of water, the pressure in the line will drop over, say, 30secs and hit 95psi. The pump will then turn back on to hit the 100psi mark again. This process will go on and on, and that's really not good for the pump.

For an irrigation system, you'd require a transfer pump that provides constant pressure.

You could likely run irrigation, but that should be done after the tap, and there would need to be enough sprinkles/drippers to cause the pump to run constantly and not switch on and off all the time. You'd need to isolate the irrigation system at the tap when not in use or have it on a timer. Once again, you'll need to check the pump's specs to ensure it's capable of running constantly under these conditions.

Please let me know if you have any questions.

Mitchell

NotHarryPotter

https://www.workshop.bunnings.com.au/discussion/comment/27691#Comment_27691

Hi Mitchell,

Many Thanks for your speedy and in-depth response.

Regarding the pump constantly wanting to recharge once the drippers were empty/below pressure; I forgot to add a non-return valve to my diagram which I hoped would be all that was needed to maintain pressure in the first half of the system and prevent the constant priming. The idea being the drippers would remain in stasis until the pump would run - either manually switched on or activated via the toilet flush or new tap use.

I managed to find details of the pump itself. It's a Bianco Pumpz model BIA-INOXG60MPCX.

A quick Google indicates a flow rate of 32psi using 1" pipe (input/output). If the average house water pressure is @50psi, I think it would struggle to provide a decent hose spray, especially after 50m. The reducing of the system to 3/4" through the fittings may help, but I doubt it would make enough difference. The pressure loss in having the drippers run while also running the tap would probably render it useless anyway!

I think (with your help) I've convinced myself to go back to the drawing board..

Thanks again.

MitchellMc

https://www.workshop.bunnings.com.au/discussion/comment/76440#Comment_76440

I should have thought of using a non-return valve, @NotHarryPotter. That would likely work.

I'd imagine you'd still get a decent spray from the hose, and I don't believe there would be a significant reduction of flow from the drippers as they have a very low rate.

Mitchell

NotHarryPotter

https://www.workshop.bunnings.com.au/discussion/comment/102132#Comment_102132

I think at the very least I should test the spray with a local setup.

Thanks again Mitchell!

toolmantaylor

https://www.workshop.bunnings.com.au/discussion/comment/118069#Comment_118069

Hi @NotHarryPotter , just wondering how you went with the pump and sprinkler system. Did you need to get a different pump? I'm thinking about a similar job so wondering how it went.

EricL

https://www.workshop.bunnings.com.au/discussion/comment/129053#Comment_129053

Hello @toolmantaylor

Welcome to the Bunnings Workshop community. It's sensational to have you join us.

Please note that any plumbing work must be carried out by a licensed plumber for safety and compliance.

Let me tag @NotHarryPotter as well to make sure they are aware of your question. One of the factors that got me thinking was the amount of water the pump was capable of doing. If you look back at the discussion, the pump was capable of doing 55L/min which conservatively if operated for 19 minutes will easily use 1045L of water. Technically in order to save water for other uses and prevent your pump from getting damaged you can only use your pump for 10minutes conservatively.

However, if you have a larger water tank then this would not be a problem, but it is always safe to calculate the amount of water you can use and how much you need to leave in the tank. It would be interesting to find out how NotHarryPotter's set up worked out.

If you have any other questions we can help with, please let us know.

Eric

NotHarryPotter

https://www.workshop.bunnings.com.au/discussion/comment/134482#Comment_134482

Hey @toolmantaylor,

Thanks for the question - I forgot to update this post/project!

I found the pressure from the pump more than adequate to run a hose directly from the tap. As Mitchell had advised, allowing the pump to be controlled via pressure and for long/constant periods wasn't a great idea. I decided to branch the irrigation from the tap line and ended up simply adding a pressure reducer/filter and controlling the irrigation via an inline timer (https://www.bunnings.com.au/orbit-irrigation-timer-controller-with-valve_p0057140) inside a valve box:

The timer acts like a non-return and the system is now constantly at full pressure and instant, and I can use the tap without interfering with the irrigation.

As Eric stated, the pump will easily drain the tank if uncontrolled. I simply run the pump for 2 x 1min periods during the day (about the same time it takes when filling the toilet), which has been adequate so far. My pump setup was installed to take its feed from the mains supply if the rainwater is drained. But I haven't notice it needing that just yet.

Please shout if you have any more questions.

EricL

https://www.workshop.bunnings.com.au/discussion/comment/137979#Comment_137979

Hi @NotHarryPotter

Thank you so much for the update and the photos of your setup. Let me tag @toolmantaylor to make them aware of your answer. The pressure reducer and the addition of a timer is an excellent work around for your 1000 litre tank. Should the opportunity present itself, I propose adding another 1000 litre tank next to your existing one to increase your watering time for your garden.

Eric

toolmantaylor

https://www.workshop.bunnings.com.au/discussion/comment/140364#Comment_140364

Hi @EricL and @NotHarryPotter, thanks for quick responses and NotHarryPotter thanks for the detailed answer! I've got some planning to do before I kick off this project but it's really useful to see what I'll need to take into consideration.

All the best!

Child Item