Frequently Asked Questions

General/Catchment Areas

• From what surfaces can rainwater be harvested (roofs, driveways, lawns, etc)?
• Is rainwater harvesting a new practice?
• What types of roofs work for rainwater harvesting?
• How much water can I harvest from my roof?
• What about people drinking from the water hose when you are connected to harvested water?
• What type of piping do you use?
• My roof is not that big. Should I even bother with rainwater harvesting?
• I keep hearing the term LEED. What is it?

Water uses

• What are the typical uses for rainwater?
• Is rainwater harvesting system easy for a typical homeowner to use?
• What is potable water?
• Do I need an electric pump to harvest rainwater?

Filters

• What is a first flush device? Do I need one?
• How does the inside filter work in a downspout or vortex filter, what is it made of, and how do you clean it?
• Are there any restrictions on how the pipe is run before it enters a vortex filter or downspout/standpipe filter? (orientation, where should pipe size transitions be made, etc.)

RWH Policy

• Who controls/regulates rainwater harvesting?
• Can only plumbers install rainwater harvesting products?

4-step process

• Don’t you want the water moving around in the cistern?
• Where are you pulling the water from in the tank (cistern)?
• Does the water in the cistern become stagnant?
• Is a biofilm bad?

Float switches

• How is the float switch mounted in the tank?

Tanks

• How do I know what size tank to install?
• What is the best product to use to backfill with the plastic tanks?
• What is the crush factor for the plastic tanks?

Municipal water back-up

• Can you use harvested water and municipal water together? How can you integrate the two?
• What happens when you go through long periods without rain?
• What is a day tank?

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General/Catchment Areas

From what surfaces can rainwater be harvested (roofs, driveways, lawns, etc)?

RMS and Jay R Smith recommend only using rainwater harvested from roofs. Rainwater from parking lots and driveways often contain significant levels of oil and other petroleum products. If rainwater harvested from these surfaces is to be used, it should only be used for irrigation and an oil/water separator must be used. Rainwater from lawns may contain higher levels of fertilizer, animal waste and pesticides. This water should also only be used for irrigation and the high nutrient levels may lead to tank maintenance issues.

Is rainwater harvesting a new practice?

No! People have been harvesting rainwater since they understood how valuable water is. New technology makes it more efficient and convenient. The practice continues to grow and in some places is mandated in new construction.

What types of roofs work for rainwater harvesting?

Rainwater can be harvested from any roof; however, some roof materials present health risks if the water will come into significant human contact. Copper roofs leach copper into the water and old copper roofs may contain lead solder. For these reasons, rainwater harvested from copper roofs should not be used for potable uses or in fruit/vegetable gardens. Asphalt shingle roofs, cedar shingle and similar types may leach some materials in the first year of use that can be harmful for human consumption. The Virginia Rainwater Harvesting Manual and the Texas Manual on Rainwater Harvesting both provide additional guidance on roofing materials. RMS and Jay R Smith recommend that all systems designed for potable use be tested for water quality prior to use.

How much water can I harvest from my roof?

A typical roof will allow approximately 623 gallons of water to be harvested per 1000 square feet in a 1 inch rainfall event. Obviously, a larger roof area will produce more harvested rainwater.

What about people drinking from the water hose when you are connected to harvested water?

Typically unless treated to meet the potable water requirements for that area, water coming from a rainwater harvesting system is considered non-potable water (not recommended for human consumption). Spigots, faucets, etc. that can be accessed by the public should be labeled with “Non-potable water. Do not drink.”

What type of piping do you use?

Our rainwater harvesting products can be adapted to all types of drainage piping. The products are designed to work with PVC pipe.

My roof is not that big. Should I even bother with rainwater harvesting?

YES! Every drop of water you harvest comes to you at no cost. Even a small system can be cost effective. It’s also just the right thing to do.

I keep hearing the term LEED. What is it?

LEED stands for Leadership in Energy & Environmental Design. It is an internationally recognized third party certification system primarily associated with buildings. LEED certified buildings are more environmentally friendly in their design, construction and operation.

Water uses

What are the typical uses for rainwater?

Outdoor uses:Irrigation, Pool filling, Washing Vehicles
Indoor non-potable uses:Toilets and Urinals, Laundry, Washing Floors, HVAC Cooling Towers, Fire Suppression

Is a rainwater harvesting system easy for a typical homeowner to use?

Yes, a properly designed and installed rainwater harvesting system requires minimum maintenance and attention and is made of durable, corrosion resistant materials.

What is potable water?

Potable water is water of high enough quality that it can be consumed with no immediate or long term ill effects.

Do I need an electric pump to harvest rainwater?

Not necessarily. An above ground tank filled by a filter located higher than the tank will operate by gravity provided there is a spigot at the base of the tank. A pump is typically required if the water is stored in a below ground tank.

Filters

What is a first flush device? Do I need one?

A first flush device is a product that allows the initial flow of water off the roof to be diverted directly to the storm drain. The initial flow draining off of a previously dry roof can contain impurities that should not end up in the tank. Our filters all incorporate a first flush action as they do not begin to filter water until the filter mesh is completely saturated. This ensures that the initial flow passes to the storm drain. Since our filters incorporate this technology, a separate device that requires maintenance is not needed with one of our systems.

How does the inside filter work in a downspout or vortex filter, what is it made of, and how do you clean it?

Rainwater enters vertically in a downspout filter or horizontally through the top inlet of a vortex filter. From there it spills into the filter element. Initially, the water and debris from the roof will flow out of the bottom outlet which is connected to the storm drain or is daylighted appropriately. This water which initially rinses the roof is commonly referred to as the “first flush.” Once the filter element has become wet from the initial flow, capillary action draws the water through the side walls of the filter element. This process filters and aerates the water which exits the filter from the side outlet and is sent to the tank. The filter will collect up to 95% of the water. As the flow continues through the filter, debris will continue to wash through and be filtered by the filter element. The remaining 5% of the water will continue the conveyance of debris to storm drain/sewer. All Jay R. Smith filter elements are made of type 304 stainless steel. To clean the filter element, attach the lifting handle to filter and simply lift it out and wash off using a high pressure hose or (if small enough) place in a dishwasher.

Are there any restrictions on how the pipe is run before it enters a vortex filter or downspout/standpipe filter? (orientation, where should pipe size transitions be made, etc.)

For proper functioning of the vortex filters and the downspout/standpipe filters, you should avoid disturbance of the flow, including size transitions, just before the filters. The small capacity vortex filter requires 4 ft. of straight horizontal pipe before the rainwater inlet; the downspout/standpipe filters should have 30 inches of straight vertical pipe above the filter.

RWH Policy

Who controls/regulates rainwater harvesting?

Rainwater harvesting falls under the jurisdiction of multiple agencies. The indoor use of rainwater will likely be regulated by the health department and the local service authority. The plumbing inspector will also have authority over the connection of a rainwater harvesting system to fixtures and the municipal water supply. The department of environmental quality (or similar agency) will have authority over the use of rainwater harvesting as a stormwater management tool.

Can only plumbers install rainwater harvesting products?

If you are located in or currently connected to a municipal system you will need to contact them for any restrictions or requirements. If you are not located in an area served by a municipal water system we would advise checking with your local or state governments for restrictions or requirements regarding rainwater use. Frequently, rainwater harvesting systems only used for outdoor uses do not require a plumber for installation.

4-step process

Don’t you want the water moving around in the cistern?

Circulation of water in the cistern to introduce oxygen and avoid development of a stagnant area in the tank is important for healthy water storage. However, water movement near the bottom of the tank should be minimized to avoid resuspension of sediment and destruction of the biofilm. That is the main reason we recommend using a smoothing (or calming) inlet.

Where are you pulling the water from in the tank (cistern)?

The floating filter takes water from a few inches below the water surface, typically the location of the cleanest water in the tank.

Does the water in the cistern become stagnant?

The water in the cistern never becomes stagnant because it is frequently circulated in the tank. Every time it rains, fresh water and oxygen enter the bottom of the tank. Because water leaves the tank from near the surface, either through the floating filter or the overflow, the water does not become stagnant. Even if a tank is not used for months, the introduction of new water (and the overflow of water that has been in the tank) with every rain keeps the water from getting stagnant.

Is a biofilm bad?

The biofilm is actually a beneficial component of the water storage tank. A stable biofilm digests organic matter and can even reduce metal concentrations in the harvested water.

Float switches

How is the float switch mounted in the tank?

Float switches are often attached to upright piping that is located inside the tank. Care should be taken so that they do not interfere with or get entangled with other components.

Tanks

How do I know what size tank to install?

Jay R. Smith Mfg. Co. offers a free service through our factory representatives that will assist you in sizing your tank. Tank selection is important as a healthy system will allow for periodic overflow of the tank.

What is the best product to use to backfill with the plastic tanks?

Please follow the tank manufacturer’s recommended installation instructions or contact them for advice.

What is the crush factor for the plastic tanks?

Please contact the tank manufacturer for specific load data for the tank you are using.

Municipal water back-up

Can you use harvested water and municipal water together? How can you integrate the two?

Rainwater harvesting systems can easily be integrated with a municipal or well water supply to provide seamless delivery of water, even if the rainwater tank runs dry. All systems should include a float switch in the tank to turn the pump off if the water level in the tank is too low. For outdoor only systems, the simplest solution for a back-up water supply is often just to have two spigots –one from the rainwater harvesting system and one connected to the municipal or well water supply. For indoor/outdoor systems, municipal water can be hard-piped to the rainwater system with an RPZ valve or similar for backflow prevention. Municipal water can also fill the main tank or a smaller make-up water tank through an air gap. Check with the local plumbing inspector for approved connections in your area.

What happens when you go through long periods without rain?

During long periods of no rain, the tank will empty and the pump will shut off. All systems should have a back-up water supply to be used during these dry periods.

What is a day tank?