Rainwater tanks save the day Part II


Connolly Dam, Warwick’s town supply, spilling over for the first time since 2011.

I had so much correspondence on this topic last week I took up an offer from guest blogger and rainwater tank owner NEALE GENTNER. He writes about his water filtration adventures working in the PNG Highlands and the hard yakka maintaining concrete tanks and plumbing over a 30-year period.

I totally agree with Bob’s piece last week on water tanks…except for paying extra rates to council for maintenance “compliance”.

Theoretically, under various “Health Acts”, tank water cleanliness is currently enforceable. No one wants to do it because of voter backlash; they will act if disease breaks out.

Over time, when replacement of pumps, filters etc is included, the real costs to install, operate and maintain a good rainwater harvest system is currently more expensive than hooking to the grid and paying water rates. Some have no choice due to location.

In 1984-1985 when I worked in PNG, I gained a lot of experience with filtration of drinking water. We were wildcat oil drilling in the Southern Highlands at 2,000M elev. The nearest village/town was Tari, the only access by helicopter, or a trek through jungle.

Everything broke down into 1,000kg heli-loads, constant heli shuttle flights; mostly diesel fuel once everything was established.

Water supply was rain run-off into an earth “turkey-nest” dam a mile or two away and lower than rig. Yes, everything that lives in the woods also craps and eventually dies in the woods, so lots of opportunity for pathogens. We used a diesel pump and 50mm steel pipeline back up the hill to rig & camp.

All camp drinking water was filtered. We just used wound-string filter elements, in clear plastic housings, elements were white when new, changed when completely brown, Most of the brown was decayed leaves etc, I forget now how long the filters lasted, probably variable, monitored daily, changed as-required.

No chemical treatment, no bad outbreaks of “squirts”, and the few minor cases were likely guys being careless. (If I knew then what I now know about water-borne bacteria, I would have taken more care).

As a child, I lived through Redcliffe City Council’s ban and enforced destruction of household rainwater tanks. But we much preferred the taste of my grandparents’ tank water in Dalby. And even Redcliffe “town” water tasted better than Brisbane reticulated water.

Chrissie’s family have only ever had un-filtered tank water. At 93 years of age, her Mum still does!  We have had two 45,000 litre (10,000 gallon) concrete tanks for almost 30 years.

We’ve never run out of water. The tank filling pipework comes from single storey roofs, goes underground, then back up to tops of tanks. Originally all the underground pipework was 90mm “rainwater” PVC. Subsequently, I have put in additional underground pipes and replaced most of the existing with 100mm “sewer” grade PVC, bedded in sand, because it is more resistant to plant root and reactive soil damage, plus it flows a lot more volume when it really rains.

About 15 years ago, I emptied, ventilated and got inside both tanks (one at a time), de-sludged, pressure blasted, wet-vacuumed, prepped and sealed cracks on the inside so water pressure helps ensure a good seal. I installed a string filter about 10 years ago. It is plumbed straight off the pressure pump, so all house water is filtered.  From what I have learned subsequently about water-borne bacteria, I’m glad the entire house is filtered. Now it just needs an anti-bacterial filter element to take it to the next level. I also installed a “first flush” plumbing system to get rid of most dry weather accumulated crud (inc frogs) to stormwater street drain. I like frogs, just not in my drinking water.

Mozzie mesh-crud strainer baskets at tank top inlets have been replaced once, the filling inlets at tank top strainers have gravity actuated, one-way flaps to stop critters entering, but allow everything out of the pipe.

A Council inspector once insisted that I put mozzie mesh on our three sewer roof vents (septic tank). He said mozzies would fly through vent caps, down vent pipes and breed. Knowing it’s a losing battle arguing with those who flex authoritarian muscle, I bit my tongue. I could have instead asked about the statistics of mozzie breeding in Council-approved stagnant water, within the underground portions of my tank filling pipe-work (before first flush installed), and the number of breeding mosquitoes at the water filled settling ponds of town water treatment plant, not to mention the actual dams & reservoirs.

But I replied “Oh Gee, mate, never though of that. I’ll put some mesh on the roof vents straight away (and I did). The “expert” was happy, I just muttered and shook my head, it was the simplest resolution.

Then there was the “drought proofing” by the taxpayer funded pipelines and pumping stations, intended to shuffle water between municipalities. Apart from its questionable effectiveness, the environmental damage and costs to some land owners was enormous. The pipeline only required a 3M wide clearing to dig the trench and get it in the ground. But the pipelayers insisted on clearing a 10M wide swathe, simply so they could turn the lengths of oversize black poly pipe around, “if required”.

Even gazetted nature reserves suffered this fate. Our illustrious water resources authorities have been vested with the power to do almost anything, with complete impunity.Then the pipelayers carted away and sold off the mostly top quality top-soil removed from trench, before backfilling with carted in “fill”, some of which was building waste.

Creative uses for rainwater tanks

The best suburban use of water tanks I have ever seen was when neighbours replaced their side boundary fence with a string of narrow water tanks, originally intended for under eave use.

Both house roofs feed the huge volume “boundary-tank”, the final over-flow is right at front fence and goes under footpath to road gutter. They chose neutral colour, roto-moulded plastic tanks with integral see-through openings/reinforcements and even left a gap for a gate so neighbours can still be neighbourly. The interconnecting feed pipe is underground for gate and overflow connects above.

Each neighbour only “lost” a 300mm wide strip of yard and it keeps the dog in. Brilliant!  Of course this requires that you get on well with your neighbour. Perhaps this is worthy of a simple Council mandate… all suburban side fences must be minimum of 600mm thick and hold rainwater. NG

Footnote by acreage dweller Joy Duck

The benefits of rainwater tanks aren’t limited to rural areas. People in the burbs used to have smallish (1000 litre) tanks to top up their pools and water their handkerchief lawns. Then the scaremongers went to work and they were removed in droves (sadly the tanks, not the scaremongers), with challenges of maintenance cited as the reason. I bought a second hand, 3000-litre tank for for the shed, from a developer who had dozens in a paddock.  He had removed them (just a year after installation), from a complex he’d built.

There is already a dedicated 22,500 litre tank and fire pump connected to our house with a rooftop sprinkler system. Because it is a fire pump, if necessary, the brigade could connect their hoses to it and use for other purposes. It’s a key start petrol pump so if the fire takes out mains water and power you still have firefighting capability.

Having a stand-alone tank and pump dedicated for firefighting can be very reassuring, if you live on a heavily treed block where the wildlife successfully  protests any attempts to clear vegetation!

Next week: On the road again!


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