Special Reports
Rainwater Capture: Tips For Getting Started

May 19th, 2008

Rainwater capture is simple in concept, and the execution is not rocket
science, but there are some key points to keep in mind:

Customers should understand that a rainwater system is composed of three
main parts, the “catchment” or roof that is supplying the runoff, the
filters and the storage tanks. says Jack Schultz, an engineer in Santa
Clara, Calif., and representative for the American Rainwater Catchment
Systems Association (ARCSA).

Most importantly, they should consider every material that will come into
contact with their water along that progression from catchment to
filtration to storage, bearing in mind that even if they’re not planning
to drink the water, they may someday want to add that function. The
storage tanks and components can be plastic or metal, such as galvanized
steel, which tends to be a bit more expensive, but also more durable. (And
with all the recent news about toxins in plastics, it would be wise to
find out what type of plastic is being used.)

Filters come in varied forms, depending on the water’s intended use and
can include screens to winnow particulate matter, all the way up to
state-of-the-art ultraviolet light filters that can kill bacteria and
viruses, making the water safe to drink, Schultz said. A rainwater
catchment expert can discuss the best filter for the system under
consideration, the best materials for a given budget and the most
appropriate placement plan for the site, he said.

One critical matter that must be discussed early on is the composition of
the roof. The roofing materials most compatible with rainwater collection
are metal (with no zinc oxide) and tile. Unfortunately, most roofs are
comprised of asphalt shingles, which shed hydrocarbons into the water. The
dirty run off from asphalt shingle roofs does not pose much problem for
irrigation water, but would require more extensive filtration if it were
used for bathing or converted to potable water, Schultz said.

So if the rainwater system is part of a new construction project, the
owner would do well to consider a cleaner metal roof, some of which also
offer reflective properties that help keep cooling costs down.
Many homeowners start out thinking they’ll just use the water for certain
limited purposes, Schultz says, but often later on they want to expand the
system’s uses, which is why the roofing material is an important early

While the rain catchment professional is assessing the house and lot, it’s
a good time for the homeowner to run the project past their city building
code office. Catchment systems generally are allowed, but placement might
be restricted, said Greg Whitfield, owner of The Rainwell in the Dallas
area. Home owners also should consult their neighborhood associations
because the group may not allow the tanks to be visible from the street.


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