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How widespread is rainwater catchment in Puna? The most common type of roof used for homes with water catchment in Puna is galvanized metal that has been painted or enameled with a nontoxic paint that does not contain any fungicides or other poisonous substances. Other materials that are sometimes used are concrete, terracotta tiles, slate, polycarbonate, and fiberglass. Being born and bred city-dwellers, rainwater catchment in Puna sounded a little too rustic for us to be comfortable with at first. But we soon learned that most homes in Puna are using this system successfully. Since there is usually an abundance of dependable rain, even in the lower-lying areas in Puna, rainwater catchment systems can be installed pretty much everywhere. The biggest challenge with rainwater catchment in Puna will not be 'harvesting' the rainwater but how to store it properly. Not just the tank, but also the condition of the roof, gutters and pipes will all affect the quality of the water and need to be checked on a regular basis. Bacterial growth in the system (especially Leptosporosis) can be quite dangerous so water storage is a serious matter. If you look at buying a home with rainwater catchment in Puna, make sure you get the facts by insisting on answers to the following questions: How old is the water tank? Cracks and leaks can increase the risk of water contamination. When was the system cleaned last? The catchment system needs to be cleaned at least once every 3 years but more often if you see discoloration of the water or sludge in the tank. For tanks with liners: How old is the water tank liner? It is also good to find out if the liner is a food grade plastic liner. For concrete or redwood tanks: What kind of paint was used to coat the tank? Oil based paint can leech lead and contaminate the water system. Is the water tank capped? Shade cloth covered tanks need to be maintained properly. Holes in the cloth can lead to water contamination and can even make it so that curious animals like cats fall into the tank and drown. How old is the water pump? There are a number of different kinds. Check with the pump manufacturer to see what the life of their product is. How old is the filter? The filter is the heart of the catchment water system, especially if you plan on using it for drinking water. Check with the manufacturer of the filter system to see how often it needs to be changed. When was the system last cleaned? All parts of the catchment system need to be cleaned regularly to reduce the chance of a clogged system, discoloration of the water and bacterial contamination. Are there any toxic coatings in/on roof, pipes or faucets? Galvanized roofing, paint, copper flashing and coated roof nails can all be a source for heavy metal contamination of zinc, copper and lead. Old lead solder on copper pipes and brass faucets can also be a source for lead contamination. All these parts need to be replaced and taken into account when you buy a house. Has the water ever been tested for bacterial contamination? Foreign materials like leaves, seeds, twigs, and also animals like cats, rats, mongoose, birds and geckos can end up in the system and contaminate the water of your catchment with their urine and feces. Make sure that the roof does not offer access for these animals. Trees should be cut back. Does the system have a first flush diverter? First flush diverters make it so that the water in the beginning of a rain (which is the dirtiest) does not enter the rainwater catchment system. When you buy a new system for rainwater catchment in Puna, make sure that:
About 75% of the residents get their water from rainwater catchment in Puna. On our first trip to Puna we noticed that most of the houses have galvanized metal roofs (like corrugated iron). At first we thought that was kind of cheap choice for roofing, (although when color coordinated properly with the rest of the house these roofs can be really attractive). But then one of the real estate agents we were working with pointed out that these galvanized roofs are the best roofs for homes with rainwater catchment in Puna(duh – should have seen that coming - who would want to have the water running off asphalt shingles!).
TIP: Copper pipes are usually coated with some kind of mineral oil derivate on the inside. I’ve seen it cause skin reactions in sensitive people. Just use a solution made with TSP (around one cup for a gallon) to get rid of this coating. I usually plug up one end of the pipe with a cork, then fill ¾ of the pipe with the solution, plug up the other end and let it sit in there for about 2 hours. Every 10 minutes I would move the pipe around a little bit, to move the solution with in the pipes. If you do that make sure to thoroughly rinse the pipes with water afterwards, because you don’t want TSP in your water system either.
Trish Macomber from the department of Natural Resources and Environmental Management at the University of Hawaii in Hilo is probably the top specialist when it comes to questions about rainwater catchment. Her free downloadable Guidelines on Rainwater Catchment Systems for Hawaii are a must for everyone who wants to know about health issues in connection with rainwater catchment, how to build a proper system and how to keep it clean and healthy.
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