Water Catchment on the Big Island, Hawaii

Understanding Water Catchment


Water Catchment tanks and systems that provide water supply to a home are common on the Big Island and are often overlooked as a critical part of the entire home purchase. As catchment systems become ever more expensive, it’s a good idea to know the status of your water storage and supply.

To Drink or To Not Drink

Owners often ask me if they should drink, cook with, wash food, clean veggies with catchment water if they have Reverse Osmosis, UV and sediment filters, even chlorine tabs in the tank. Far from being a water quality expert, I do have plenty of experience installing systems, tanks, pumps and repairing every part of a water system…. and experience that water system people don’t have…. building, repairing roofs and gutters. As an inspector, I see a lot of roofs. And the roof is where most catchment water is collected. Metal roofs mostly.

In the early morning, a Myna bird hops about your roof and skewers a couple unlucky geckos who thought they’d catch the first rays to warm-up. Every morning, making a racket, waking you up. I go up on that same roof. There’s bird squirts with berry seeds and several half-eaten geckos soaking in a puddle of the low spot in the gutter. Just waiting to get swept into the catchment at the next downpour.

Dead birds, slugs, algae, mildew, wind blown grit, grass and plants growing from a mud clog, leaves leaching acids and tannins. All found on your roof and in your gutter. And those are the least of your worries. Fading and chalking metal paint, rust, deteriorating screw heads, tar, caulking, tape, foam, butyl sealant, paint repair, solar pipe insulation, neoprene, old fasteners with lead, gutter caulk, pvc and glue and an old slippah. I’ve seen workers lunches, cigarettes and half drunk soda bottles. All deteriorating in sun and draining into your catchment. Can a RO system clean that up? Probably. Until it doesn’t.

Not everybody’s roof, gutter is that bad. Many people keep up on maintenance and keep it clean. I power wash my roof twice a year, but No, I do not drink or cook with my catchment water.