I have some experience with collecting rainwater in the tropics. Both for household use and for increasing success of tree plantings in semi-arid conditions.
Collecting rainwater from the roof of the house where it is to be used can be very practical in many areas. When living in the northwest corner of Tanzania 1988-89, we built a rainwater tank with a couple of refinements that worked well.
Division of the tank into top part (to save the potential energy of the water entering the tank which provided a higher pressure {with better water flow} even when the tank contained a small amount of water) and a bottom part to save the overflow from the top as a long-term storage..
Use the top of the tank as one of the “collection roofs”. Water tanks are usually covered for many good reasons (prevent algae growth, mosquito breeding, evaporation, limit direct contamination). But this often has resulted in that the rain which happens to land on the tank itself, runs off to no use, while the rain which hits the roof of the house next to it is carefully lead into the tank. The house had a roof area of about 42 m2 so using the top of the tank (>2,5 m2) increased the effective area with 6 % (actually more because we weren’t able to put gutters on the whole house perimeter). Capturing the rain on the tank top was done with a small cement mortar ridge along the edge.
Usual rainwater collection tank - the usual rainwater collection tank. The rain that hits the tank itself runs off the roof. The water that enters the tank goes directly to the bottom. When there´s not much water in the tank, there is no "head" (pressure) to send it to a tap of useful height.
Rain water tank with head pressure - This kind of tank we used. It collects even the rain that falls on the tank itself. The water stays at a high level until the upper tank is filled. This gives enough "head" to supply water even to a shower that is not too high, even when there is little water.
Very clever idea, does anyone sell this type of tank in Australia?
Hello Greg,
Unfortunately I am not sure. I will put the word out on my “Helping others” page of this website and lets see if someone can help us answer that question.
Nice! Did you draw these designs yourself? Is that a support holding the first level up in the second drawing? I’ve been reading about building my own ferrocement tank. “Water Storage” by Art Ludwig is a pretty good resource for this and it doesn’t seem too hard.
Also, I’m wondering how I would hook it up to my current water pipes that use a standard well with a bladder. Any hinters here? I guess I could use a valve and switch back and forth between the rainwater tank and the well, but it would be nice if I could use the well to supplement to the rainwater like a solar hot water heater hooked into an electric hot water heater.
Thanks, I’m happy I found your blog!
I did not draw this design. I have the link of the source in my blog post. Maybe you could contact the author of this post to help you answer any questions that you may have as I am not sure if I am able to help you with this unfortunatley.
Nice post..The method you have described for the tank to storing the water is really clever.. its really nice.
Wow! nice things as collecting rainwater from the roof of the house where it is to be used can be very practical in many areas. It is also best method for collecting water and used in as permaculture power.