All drinking water at Milkwood Farm comes from the sky. This means catchment and storage of drinking-high quality water is a very massive deal for us. And since we’ve obtained the opportunity to outline the quality of our drinking water here (a luxury so many hundreds of thousands of people wouldn’t have), we’re decided to get it as wholesome as we probably can. Each for our household, and for this planet of ours.
Which led us to the seemingly mundane however actually fairly advanced activity of choosing water tanks for drinking water. Which kind to go with? Plastic, aquaplate, cement or stainless steel?
Our criteria for deciding on our drinking water tanks have been thus; glorious water quality, relatively low embodied power, and affordable. Which made our process of choosing trickier than we first thought.
However resolve we did, and we thought we’d share the outcomes of our analysis here in case they’re of use to others. This isn’t the ultimate word on water tanks, however it’s the product of our 6 months of researching, speaking and interested by how to steadiness our standards to present our farm the very best drinking water system we are able to presumably devise:
A comparability of water tank supplies for drinking water
PLASTIC WATER TANK
Supplies: food-grade polyethylene, the same stuff used to make plastic food containers like tupperware and many others, and regarded the safest type of plastic. Has added UV stabilizers to stop the plastic breaking down exterior, and plastic softeners to make it flexible. BPA softeners may be used (i never might get a transparent reply on that from any manufacturer).
Toxicity: At the drinking finish, I’ve problems with this option. Plastic softeners like BPA will not be what you need in your child’s tummy because the tank supplies go although their inevitable off-gassing course of. Softened plastics are additionally closely related to endocrine disruptors.
Also, being outside, these tanks break down over time, regardless of the UV stabilizers (couldn’t find any data on the UV stabiliser off-gassing qualities, either. Hmm). When a substance breaks down, meaning it goes somewhere else. Like into the assorted cycles of our farm. Double hmm.
Enviro-cred: Plastics are, as I’m sure you understand, made from oil which isn’t that great. Their embodied power throughout manufacturing is fairly excessive too. A lifetime of 25 years means they don’t stay eternally, and at the tip of that time, due to the UV degradation, they’re not considered recyclable in Australia. In any respect. Which again ups their embodied power. Transport to site is important, unless you reside next to a plastic tank manufacturing facility.
Set up: lifeless straightforward. All that’s required actually is a stabilized flat spot. Because plastic tanks have a small amount of flex in them, they’re a bit extra forgiving than other materials on the subject of installing. Some of these tanks are available in a variety of sizes and shapes, which may help installation.
Price: Plastic tanks are a cheap possibility, at across the $2,600 mark for a 22,500L tank. Supply extra.
Our verdict: the toxicity and embodied energy didn’t make this selection attractive at all, despite it’s worth tag. Would doubtlessly additionally melt in a bushfire, inflicting us to don’t have any water. Not good.
CORRUGATED IRON WITH PLASTIC LINING WATER TANK
Supplies: The trendy version of the basic Aussie corrugated iron tank. Aquaplate® is the most common material used. Aquaplate® is corrugated steel on the surface with a spray-on plastic polymer lining. As far as we all know, all corrugated steel tanks (besides stainless steel) are now bought with this plastic lining, to stop rust and to prolong the life of the tank.
Toxicity: The primary problem with these tanks to me is the spray-on polymer that types the plastic lining of the tank. Not a lot data may we find on the polymer plastic lining, except that it doesn’t need the UV stabilizers in it because it’s not exposed to sunshine. But any means you look at it, it’s spray on plastic, instantly involved along with your drinking water.
Softened plastic in constant contact with drinking water will not be my idea of a wholesome time. Once more, see hyperlinks to BPA, endocrine disruptors or do your individual research.
Enviro-cred: Not too unhealthy. The steel production has lots of embodied power (about 2/three of a plastic tank), but this could, in idea anyway, be offset by recycling the product at the top of its 25 years guarantee. How they get the bonded plastic lining off to re-use the steel, no-one can tell me but. So that sounds just a little theoretical to me.
There’s also the possibility that the steel made to use the tank could also be recycled already, which can be great, however not a given, so it’s arduous to rely on it. Once more, transport to site is needed.
Installation: Fairly easy you want a great stable flat pad to put it on, however it’s pretty much a case of plonking it down and hooking it up to a down pipe. These kinds of tanks are available in a wide range of sizes and shapes, which may support set up.
Value: Around $2,800 for 22,500L, relying on shape and location. Supply additional.
Our verdict: higher than plastic (at least on the embodied energy front) but too many questions about toxicity of the polymer lining for this to be an option.
CONCRETE WATER TANK
There are two options for concrete tanks as much as 15,000L tanks will be forged off-site and delivered, or for bigger tanks the only choice is to make them on-site. As we’re talking in the 22,500L vary, we solely investigated the cast-onsite possibility.
Materials: Product of concrete with steel reinforcing. All concrete sold in Australia now incorporates fly ash, which is the scrapings from throughout the chimney of coal-burning furnaces. It makes concrete stronger. Concrete’s other components are sand, gravel, lime and water.
Toxicity: Not dangerous in any respect, as far as we can inform. Concrete tanks have traditionally been thought-about to supply superior quality drinking water as a result of the good thermal mass of the tank offers a stable water temperature. This means less warm spots, and subsequently much less algal blooms. It is also usually commented that concrete tank water has a nicer taste. This might be because of the varied minerals leaching from the cement tank into the water. There are numerous stories about fly ash toxicity that made us marvel about it’s well being effects when included in concrete, nonetheless.
Enviro-cred: Not so good. High embodied power (about the identical as a plastic tank for the same size). There’s also ethical questions concerning the sourcing of sand, as much sand mining occurs in environmentally sensitive areas. Not recyclable, which implies no likelihood of off-setting your guilt in regards to the embodied vitality. A well made concrete tank ought to final a really long time, however, which is a plus.
Installation: More complicated than a simple delivery. Requires a crew to come out, prep site and pour tank. Tank pad must be very effectively made and stable, or tank might crack. Some logistics to think about with entry for concrete truck to tank site, weather, and so on.
Worth: comparatively costly around $four,000 for a 22,500L tank put in.
Our verdict: better than the options containing plastics, but still some toxicity questions. The non-recycleability also made it hard to get excited about this feature.
STAINLESS STEEL WATER TANK
Exploring this selection seemed a bit dumb, initially surely it can be incredibly expensive and no-one made them anyway?
Materials: Stainless steel, which is iron with added chromium and/or nickel.
Toxicity: Stainless steel is taken into account to be very secure and preferable for a lot of applications, therefore its use in surgical equipment, catering, drink bottles and so forth. So far as we could tell, if you don’t heat it up or ingest shavings of it, it’s just about inert.
Enviro-cred: High embodied energy in production, however 100% recyclable. Completely and completely. Due to its excessive value, the probabilities of the stainless steel having had multiple lives earlier to its incarnation as a water tank are also high. Ought to final a lifetime if we don’t back a truck into it, which ups its cred further.
Set up: comparatively straightforward, with good strong pad ready. Like plastic and aquaplate, a simple operation of supply and placement.
Worth: pretty costly around $four,000 (delivered) for 22,500L
Our verdict: costly upfront, but when its all said and finished, price it. Very low toxicity means excellent and protected drinking water, and in 70 years time our grandchildren can use the steel for something else (or cash it in).
Whew. So that’s the wash-up. We ended up getting two 22,500L stainless steel tanks, which, when full, will guarantee our household of loads of drinking water all 12 months spherical, even within the 100-12 months drought. The tanks value us $8,000 delivered from Stainless Steel Water Tanks in Brisbane, but there are now fairly a few stainless tank suppliers Australia wide.
A notice: we made our choice primarily based on our site’s constraints, and our time and money budgets. If our rocky ground could have confidently harbored an in-floor concrete cistern with out us spending $20,000 digging round for a subterranean boulder-free spot, we might have taken this feature.
Also, the data above is not supposed to make anybody feel inadequate or worried about their present rainwater tanks, we just thought we’d share what we discovered in the process of constructing our selection. Hooray for rainwater, in all its contained varieties. And to anybody already catching and storing this energy.