Plumbing Plan: Collecting Rain Water

As I hope to strive towards an off-grid lifestyle, I decided early on that I want to harvest rainwater. Fear not, I am not naïve to fact that it’s unlikely that I will be able to collect enough to meet the demands of the house, but at least a little is better than nothing. I admit I am curious as to how much this ‘some’ will be, however as I don’t know where I will be planting my house, I will leave this for a future date.

So whilst the numbers are all unknowns at the moment, I still needed to gain a better understanding of the ‘how’ behind rainwater harvesting. To do so, I read Michael Mobb’s book ‘Sustainable House: Living for Our Future.’ This book breaks down the process Michael went through to convert his Sydney house into an almost self-sufficient home. Though a fair amount of the information isn’t truly applicable to a Tiny Home, it was an excellent read and the chapter on Water was incredibly helpful. I recommend checking out his site– this particular post talks about his water system. If you can get your hands on a copy of the book, it covers this in more detail.

I have watched a couple of YouTube videos which do capture Tiny House water set ups, but they seem few and far between so please, if you have seen any others do share below! Here is one which shows a more permanent set up, and another which doesn’t collect rainwater but provides an insight into alternative options.

Just quickly, I wanted to note that I am now remembering why in the past, I have repeatedly fallen out of the habit of blogging. I am a pretty pedantic writer and will read over and over a sentence to ensure it’s spot on. This becomes most unproductive and in the end don’t have time to post. In an effort to avoid this, I have decided that I will only post about stuff I am currently researching, meaning I’m afraid I won’t be covering information I already have stored in my brain. Whilst I will try to provide some helpful links if I come across such areas, I won’t go into detail myself.

I mention this now because I was about to explain how rain is collected from the roof, but to be honest, I already know this back to front and so will be skipping past, but I will attach a scan of my notes. (I do apologise – my handwriting’s a little scrappy! However my past research has been fairly erratic, so though I have the guttering down pact, I am yet to look into the actual storing of the water, this would be a good of time as any to fill this hole.

As I don’t have a loft, and therefore miss out on the extra storage space this can offer, a sneakily disguised indoor tank doesn’t seem a viable option for me. As a result, we are currently thinking of popping a tank under the trailer instead. Fortunately, there appears to be a large market of under carriage caravan water tanks. Unfortunately, the majority seem to max out at 90 litres. I really didn’t have any idea as to what the typical Tiny House water tank capacity is, but this did seem a little on the small side so I had a quick look to see what others have opted for. Below are some examples:

Build Tiny– Gina Stevens: Fresh Water Tank 340L/Grey Water 360L
Tiny House, Giant Journey: Fresh Water 175L/ Grey Water 57L (see video listed in Plumbing Plan- Connecting to Mains)
Brett (feat. on Living Big Tiny Home): 380L Fresh Water
Bryce Live Big Tiny Home: 220L Fresh Water + 90L Hot Water

All a tad bigger than 90 litres..hmm, clearly this warrants further investigation.
It would also appear that one should know the catchment area of their roof. This can simply calculated by:

[House Length x House Width= Roof Square Metres]
So in my case: 6 x 2.5 = 15 square metres.

Now, this is a very small catchment area, especially if you consider that the average Australian home would have a catchment area of around 200 square metres, however at the same time a Tiny House uses considerably less water than a regular home.

Once you have your catchment area, you can work out how much rain you can harvest, though you will need to know the approximate rainfall for you area. This can be found online. (Australia)[Rainfall (mm) x Roof surface area (m2) = Harvestable rain] 


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