From home to work to community
In addition to household use, rainwater catchment systems are also used for commercial or community purposes such as schools, agriculture, businesses, camps and military installations. Accessibility to onsite water through rainwater catchment makes it possible to provide basic services in places where it would otherwise be impossible.
What will I need to do if I have a catchment system?
Users need to keep the roof, pipes and tank clean. Filters, chemicals and water disinfection treatment systems are needed to kill bacteria, viruses and protozoa that may be in the water which may cause illness. You are responsible for your own water system and need to be aware of it status on an ongoing regular basis with monthly maintenance and water testing.
Is the water safe?
Safe generally means no bacteria, viruses, harmful chemicals or metals are present. In the end, water quality and safety depend on the system's design and maintenance. However, with the proper maintenance, filters, and disinfection, water from a rainwater catchment system can be safe for all use and consumption.
Is rainwater catchment common?
Rainwater catchment has been around sense the beginning of time and still is used in may parts of the world such as India, England, Germany, China, Japan, Australia and New Zealand. Many states in the United States either encourage it out-right or allow with restrictions such as Ohio, Kentucky, Florida, Texas, California, Oregon, Washington and Hawai'i.
According to University of Hawai'i at Manoa in 2010, 30,000 to 60,000 people in the state of Hawai‘i are dependent on a rainwater catchment system for their water needs. The majority of those people are located on the island of Hawai‘i in the Puna, Ka‘ū, and Hāmākua districts.
It is very important that those using water from a rainwater catchment system understand all of the potential dangers. In Hawai‘i, there are no government agencies overseeing the safety of your rainwater catchment system. It is up to you as the owner or user of the system to know how to maintain the water source and use it in a manner appropriate for yourself and your family.
With proper design, maintenance, water treatment and disinfection, a rainwater catchment system can provide self-reliance in water sustainability relatively free of contamination, this water can be used for showers, drinking, washing food and dishes.
It is very important that those using water from a rainwater catchment system understand all of the potential dangers. In Hawai‘i, there are no government agencies overseeing the safety of your rainwater catchment system. It is up to you as the owner or user of the system to know how to maintain the water source and use it in a manner appropriate for yourself and your family.
With proper design, maintenance, water treatment and disinfection, a rainwater catchment system can provide self-reliance in water sustainability relatively free of contamination, this water can be used for showers, drinking, washing food and dishes.
Water pollution hazards for rainwater catchment systems
Many sources of pollution can affect rainwater catchment systems.
With awareness, planning, and good catchment system management practices, your water supply can be improved.
- Erupting volcanoes, fireplaces, and other sources of combustion produce smoke and fumes containing particulate matter that can land on your roof and wash into your water supply. Gasses from these sources also can combine with moisture in the atmosphere to produce acid rain.
- Agricultural fields nearby can be sources of pesticide drift if sprays are applied incorrectly.
- Trees and shrubs that touch or overhang the roof and gutters can cause several problems. Plant debris can block gutters and downspouts so water can’t get to the tank. Decomposing organic materials provide nutrients for microorganisms and can taint the water so that its color and taste become unappealing. Plants also host insects, birds, and other animals whose wastes and corpses can contaminate your water supply. Rats in particular are a potential source of disease, and they are adept at getting onto roofs via branches and utility wires.
- Downspouts that are not properly designed hold water between rains called wet-piping. This water is not affected by water purification treatments applied to the tank, and it stagnates while waiting for the next rain to flush it into the water supply.
- Birds delight in the baths formed by sagging mesh tank covers or blocked gutters. Many insects, particularly mosquitoes, dragonflies, and even snails find these pools perfect for breeding. Holes in the cover allow critters direct access to your stored water. Rodents and larger animals such as chickens and cats have fallen through holes in tank covers and drowned.
- Uncontrolled tank overflow can undermine a tank’s foundations, resulting in eventual tank collapse. This runoff needs to be directed to avoid causing problems on your property or your neighbor's. Tank overflow is another opening for animals to access the water by coming and going at their leisure.
With awareness, planning, and good catchment system management practices, your water supply can be improved.
Self-reliant, environmentally friendly, off-grid lifestyles makes sense.
- Makes use of natural resource and reduces runoff.
- Encourages conservation.
- Makes it possible to live in non-invasive ways using solar off-grid and water which do not deplete the earth.
- Catchment is a "green" alternative and a vital part of the reduce/reuse/recycle process.
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Building Materials
Only materials approved by the Food and Drug Administration (FDA) or the National Sanitation Foundation (NSF) should be used to catch drinking water.
The key to choosing building materials for a rainwater catchment system is to select and use materials that will not leach toxins into the water under either normal or acid rain conditions. The material should be both nontoxic and inert (nonleaching). Acid rain, which is produced in Hawai‘i as rain mixes with volcanic emissions, causes certain metals and other materials to leach much more than normal rain would. The more acidic the rain at your location, the more likely you are to have a problem with chemicals leaching from materials the water touches. Adding minerals to the water inside the catchment tank promotes a coating protecting erosion from metals components in the pump and hot water heater.
The key to choosing building materials for a rainwater catchment system is to select and use materials that will not leach toxins into the water under either normal or acid rain conditions. The material should be both nontoxic and inert (nonleaching). Acid rain, which is produced in Hawai‘i as rain mixes with volcanic emissions, causes certain metals and other materials to leach much more than normal rain would. The more acidic the rain at your location, the more likely you are to have a problem with chemicals leaching from materials the water touches. Adding minerals to the water inside the catchment tank promotes a coating protecting erosion from metals components in the pump and hot water heater.
Roofing
The most common type of roofing material used for water catchment is galvanized metal that has been painted or enameled with a nontoxic NSF approved paint. Other materials that could be used are concrete, terracotta tiles, slate, polycarbonate. Paint used on the roofingmaterial 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. Avoid using roofs that contain uncovered galvanized metal, zinc, asbestos (which can be mixed into concrete tiles), tar, asphalt, or pesticide-treated wood.
Gutters
Gutters should be made of inert materials. Commercially installed gutters are made of seamless aluminum, PVC or CPVC plastic. Copper, for example, is not a good choice for a gutter collection rainwater for household use and consumption. When installing gutters, make sure that there is a slight continuous downward slope toward the catchment tank. Low areas that cause a back flow or puddling must not be allowed. Standing water can collect insects, attract animals, and catch organic materials, such as leaves. Decaying organic material can ruin the taste and color of the water and cause health problems.
Leaf Screen
Gutter screens keeps large debris out of the storage tank. Screens require monthly maintenance and they don’t prevent small particles from being washed into the tank.
Downspout screens also prevent large debris from reaching the tank. These are easier to keep clean because they are usually within reach and cleaning them does not require a ladder. A tilted screen allows debris to slide off.
Downspout screens also prevent large debris from reaching the tank. These are easier to keep clean because they are usually within reach and cleaning them does not require a ladder. A tilted screen allows debris to slide off.
First Flush Diverter
Fitting an appropriately sized First Flush Water Diverter is critical to achieve good quality water. Water Diverters improve water quality, reduce tank/cistern maintenance and protect pumps by preventing the first flush of water, which may contain contaminants from the roof, from entering the tank/cistern.
When it rains, water slowly builds up in the roof guttering system before it exits through the downspout. The first flush of water from the roof can contain amounts of bacteria from decomposed insects, bird and animal droppings and concentrated tannic acid. It may also contain sediments, water borne heavy metals and chemical residues, all of which are undesirable elements to have in a water storage system.
When it rains, water slowly builds up in the roof guttering system before it exits through the downspout. The first flush of water from the roof can contain amounts of bacteria from decomposed insects, bird and animal droppings and concentrated tannic acid. It may also contain sediments, water borne heavy metals and chemical residues, all of which are undesirable elements to have in a water storage system.
Overflow Device
An overflow design will keep the water below the top preventing overflowing over the sides which will undermine the tank's foundation and over time cause it to collapse. An overflow device also avoids flooding near your tank or house. Screen or nylon on the vents openings keep unwanted pests out.
Floating Intake Device
Most rainwater catchment systems draw water from the bottom of the tank where sediment, decaying leaves and other organic materials often settle. When water is pulled out from the bottom it carries a lot of this debris with it. The dirtier the water is that gets pulled from the tank, the faster it will clog filters and more likely to contain unhealthy contaminants. A floating intake device can help improve water quality by drawing water from closer to the surface, which normally contains less debris and contaminants than the bottom. All this translates to better water quality and saves time and money.
Filters for Rainwater Catchment Systems
Essentially filters are screens made of various materials including paper, string, charcoal, sand, clay, silver, and even membranes. In rainwater catchment systems filters take particles out of your water. Filters are used in various locations for a variety of reasons. Typically a home would have a screen filter before the tank, a sediment and carbon after the pump and maybe a fine filter at the sink. Sediment filters come in a wide range of microns; 1-30 and are located at the point-of-entry. Charcoal and carbon block absorb chlorine, metals and debris with a chemical attraction which makes the water clearer. These filters are often used to remove bad taste and odors. They generally come in a range of 1-10 microns and are located at point of entry and/or point of use. Absolute 1 micron filters are designed to keep protozoan cysts out of the water. They are often used at the sink or point of use locations since their tiny size restricts water flow. They do not remove bacteria or viruses. Membranes filter for reverse osmosis (RO) systems are high pressure ranging from 30 to 250 PSI water molecules through a dense layer of polymer or plastic which prevents solutes such as salt ions from going through. Membranes are usually preceded by charcoal filters since chlorine can damage RO membranes .0001 micron or larger and are located at point of use or point of entry.
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