climateXchange

It's particularly important to read through the ACT Government's “Rainwater Tank Guidelines for Residential Properties in the ACT“. I'm planning to install a tank at the moment, and it's not as straightforward as I thought. For example, I found out in the guidelines that:

• There has to be a strong, level and continuous base for the water tank because it and the water weigh so much (my comment: the people who quoted me to install a water tank said they could prepare the base but would charge plumber's rates and so suggested it would be cheaper to get someone else to do it first)
• Fine mesh screens need to be properly installed on inlet and outlet points to prevent insects such as mosquitoes getting into the tank
• A pump may be needed if the tank is linked to a dripper system in the garden and/or a fitting in the house such as a toilet (if gravity can't do the work)
• A first flush diverter can improve water quality in the tank by preventing the first flush of rainwater from the roof gutters (thay may contain leaves etc) from entering the tank (not sure if a diverter is needed if the water is not for drinking)
• Tanks, covers, plumbing pipes and fittings should be light proof to minimise the chances of algal growth in the tank water
• The tank system needs to be maintained eg regularly checking gutters are clean, checking rainwater is not ponding in roof gutters, desludging the tank when needed (not sure how often this would need to be done)
• Plumbing approval and special standards are needed if the tank delivers water to taps, fixtures or appliances in the house and, in this case, ACT Planning and Land Authority (ACTPLA) needs to be notified (I presume the plumber installing the tank organises this?)

Anyway, I really suggest you read the ACT Government's guidelines and the rebates information before you install the tank.

Post edited 9:09 pm - April 14, 2010 by marea

Latest update:

The tank installation has almost been completed (there were some delays as the plumber and I were available at different times, and so the work had to be done in stages).

First, a foundation had to be established for the two tanks, so loose soil was removed down to the solid ground, and aggregate laid down. The slimline tanks were placed on top of this solid surface, a few metres apart and attached to different downpipes. First flush diverters were installed to get rid of the first flush of water from the gutters and so ensure leaf and other matter don't get into the tanks (I already have gutter guard and so wasn't sure I really needed the first flush diverters but thought it was better to be on the safe side). I hadn't realised before that these first flush diverters meant additional pipework. They are tucked away though and will look okay when all the pipes are painted the same colour as the wall.

However, due to the sloping ground, the tank further down the slope was raised onto concrete blocks and sleepers to make it level with the other tank. That enabled a similar water level in the two tanks once a connecting underground pipe was installed between the two tanks. Then the pump was installed next to one of the tanks, along with a tap to which I can attach a hose or drip system for watering the garden. There is a lot of water in the tanks already due to recent heavy rain.

The next steps are to get an electrician to install an external powerpoint for the pump, and for the plumber to connect the water tanks to the internal toilet so that I can use rainwater to flush the toilet. The idea is to use the rainwater to water the garden in the summer and flush the toilet in the other seasons. That connection of the water tanks to an internal appliance such as a toilet is also necessary to be able to claim a rebate under the ACT and federal Government rainwater tank rebate programs.

Hi Marea,

I installed a rain water tank a few years ago. The tank was fine but my submerged, stainless steel pump: 1. was very expensive (about $1,000)  2. cost even MORE to install. 3. was more noisy than we expected and 3. increased our energy use and 4. stopped working after a few months. We actually felt relief that it stopped.

I thought, 'there MUST be a better way' and there is. We have been running two toilets successfully for the past 6 months on 100% rain water with NO pumping at all. How? First we replaced the old float valves in each cistern (toilet tank) with TWO new Fluidmaster float valves (one each side of the cistern. See diagram in the ACT Gov. water tank guidelines,  page 9 – so, yes, this is legal etc. One float valve is permanently connected to the mains and the other is permanently connected to the rainwater tank (with a stop cock in each case). These valves cost about $20 each from Bunnings – (Fluidmaster 400UK063).

Now for the tricky bit. Tank water is LOW PRESSURE. We only had about a meter of ‘head’ – max. That is seriously low pressure and not enough to operate the rubber flap in the Fluidmaster that we had installed. Then I noticed a small paragraph on the side of the box the Fluidmaster came in which indicated that a low pressure rubber flap was available. So I rushed off to Mitchell, bought one for a few bucks and it DIDN'T WORK!! Next I phoned Fluidmaster ‘s Australian help line 1800 808 179 and explained the problem. BINGO, they have a SUPER low pressure rubber flat. It worked perfectly!

So now my two toilets work fine until my rain water tank gets down to about half empty. After that, I could need to turn the mains back on, but I haven't had to yet! Note that with this low pressure set up, the refilling of the cistern is slower than with high pressure refilling and it is totally silent. 

Another thing that has helped my rainwater last so long (apart from many summer showers) is that I replaced the dual flush mechanisms with much simpler 'lift' knobs. The lift knob only allows water to pass while it is held up. Thus one only holds it up as long as is needed – which, according to Derek Wrigley – reduces water consumption to about 25% of the normal DUAL flush rate. I haven't done any measurement, but I can vouch that it is a big improvement on normal dual flush. Interestingly, an old, single flush cistern can be just as easily (or more easily) converted to a lift knob system. I can't imagine why we still can't buy a lift knob systems in the shops. 

Although this works well – with zero energy use and no noise, you will probably not find a plumber who believes it works. Good luck!

Well, I've been operating the water tanks a couple of months and they've been great. The only problem I've noticed lately is that the pump comes on sometimes for a short while even when I haven't flushed the toilet. I don't remember it happening before, although it could have been happening and I wasn't aware of it. It's a bit annoying when it does this at 1.00am, even though I only notice it if I'm awake at that time.

Any ideas why it could be doing this?

The only thing I can think of is that my set-up ensures both tanks have the same water level and so maybe there is some shifting of the water level during the day and night that leads the pump to get involved in restoring the balance.

Oh no! Guess what! The watertank pump was working continuously today, so I went to see what was going on.

Sure enough, there is a hairline crack in a plastic screw connecting the hose on the other side of the pump from last time, and so water is spurting out of there. This is causing the pump to work non-stop. I can't believe the same problem is happening twice in the space of a month. Anyway, the distributor is very helpful and is coming over in the next couple of days to fix it.

The moral of the story is to look very carefully at all the components when you buy and install your pump (mind you, I don't think I would have been able to tell the difference anyway between a good and bad connector).