02-25-2010, 11:44 AM
From the UH brochure on catchments.
Roofing
Ideally, only materials approved by the Food and Drug
Administration or the National Sanitation Foundation
would be used to catch drinking water. Unfortunately,
no roofing materials have been approved for drinking
water catchment use. The National Sanitation Foundation
has approved epoxy coatings for drinking water use
that can be painted over a surface, but these coatings are
very expensive, have an effective life span of only about
seven years, and were made for coating the interior of
tanks rather than roofs and gutters.
The most common type of roofing material used for
water catchment is galvanized metal that has been
painted or enameled with a nontoxic paint. Other materials
that could be used are concrete, terracotta tiles,
slate, polycarbonate, and fiberglass.(2) Paint used on the
roofing material should not contain fungicides or other
poisons that could leach into the water. Materials containing
lead should not be used anywhere in the catchment
system. Lead is a serious problem with older homes
because not only the paint but also nails, flashings, solders,
and gutters could contain lead. Lead-based paint
was not manufactured in the United States after 1978,
but these paints were still in circulation after that time,
so if your home is an older home it would be wise to
have the paint checked. Simple, inexpensive test kits
can be purchased at local hardware stores to test paint
or surfaces for lead. In addition to lead, avoid using roofs
that contain uncovered zinc, asbestos (which can be
mixed into concrete tiles), tar, asphalt, or pesticidetreated
wood.
With a new roof, always divert rainfall away from
the catchment system for the first few rainfalls. Let the
roof rinse off and weather a bit before attaching the gutter
system to the tank. The first rains will help flush away
dust and debris such as metal shavings from the new
building materials and keep these materials out of your
tank. New paint, especially acrylic paint, could leach
substances such as detergent into the tank that could
cause the water to froth.(2) Before connecting your tank,
catch some runoff in a jar and check to see if the frothing
has stopped.
In designing a roof for catchment purposes, keep its
pitch relatively low to maximize the amount of water
that gets into your gutter. A steep roof can cause water
to splash out of the gutter.
Roofing
Ideally, only materials approved by the Food and Drug
Administration or the National Sanitation Foundation
would be used to catch drinking water. Unfortunately,
no roofing materials have been approved for drinking
water catchment use. The National Sanitation Foundation
has approved epoxy coatings for drinking water use
that can be painted over a surface, but these coatings are
very expensive, have an effective life span of only about
seven years, and were made for coating the interior of
tanks rather than roofs and gutters.
The most common type of roofing material used for
water catchment is galvanized metal that has been
painted or enameled with a nontoxic paint. Other materials
that could be used are concrete, terracotta tiles,
slate, polycarbonate, and fiberglass.(2) Paint used on the
roofing material should not contain fungicides or other
poisons that could leach into the water. Materials containing
lead should not be used anywhere in the catchment
system. Lead is a serious problem with older homes
because not only the paint but also nails, flashings, solders,
and gutters could contain lead. Lead-based paint
was not manufactured in the United States after 1978,
but these paints were still in circulation after that time,
so if your home is an older home it would be wise to
have the paint checked. Simple, inexpensive test kits
can be purchased at local hardware stores to test paint
or surfaces for lead. In addition to lead, avoid using roofs
that contain uncovered zinc, asbestos (which can be
mixed into concrete tiles), tar, asphalt, or pesticidetreated
wood.
With a new roof, always divert rainfall away from
the catchment system for the first few rainfalls. Let the
roof rinse off and weather a bit before attaching the gutter
system to the tank. The first rains will help flush away
dust and debris such as metal shavings from the new
building materials and keep these materials out of your
tank. New paint, especially acrylic paint, could leach
substances such as detergent into the tank that could
cause the water to froth.(2) Before connecting your tank,
catch some runoff in a jar and check to see if the frothing
has stopped.
In designing a roof for catchment purposes, keep its
pitch relatively low to maximize the amount of water
that gets into your gutter. A steep roof can cause water
to splash out of the gutter.