Rainwater Harvesting for Drylands and Beyond by Brad Lancaster

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Full Port Valves for Gravity-Fed Tanks/Cisterns

A full-port valve retains the full interior diameter of the pipeline it is connected to. This results in less reduction in flow (and less surface friction) than is caused by using standard valves, which have a smaller interior diameter than the incoming pipe.

Full-port ball valve on the left – great for gravity-fed systems; note how the interior diameter is not constricted. Constricted valve on the right – bad for gravity-fed systems; note how the interior diameter is constricted at the valve gate. Full-port valves maintain their full/maximum interior diameter throughout, as opposed to many valves, which reduce/constrict their interior diameter. Such constrictions can greatly reduce the flow volume and velocity of water from a gravity-fed cistern, which is typically a low water-pressure system. Don’t reduce your gravity-fed cistern water flow with a constricted valve. Instead, use a full port valve for good, convenient flow.

NOTE: I typically plumb 1 inch (25 mm) interior-diameter pipes (as opposed to smaller diameter pipe) from a gravity-fed cistern to full port valves and spigots where I want to use the water for the same reason I use full port valves.

Some full port valve options:

Pro Flow brand

At Ferguson Enterprises the full port valves are item number
PF71QTF and the description is “3/4 QT BRZ IPS Hose bib no kink.”
A more user-friendly description is: 3/4″ IPS, brass, quarter turn, no kink hose bib.
The 3/4″ IPS is the size reference; it’s made of brass; the body style is a no-kink hose bib and it needs only a quarter turn to fully open.

Mueller (made in Italy and/or China)
Ball valve – full port (Valvula de bola – con rosca – lumbrera completa)
3/4 inch 107-824
1 inch 107-405HC

Mueller (made in China)
3/4″ ball valve hose bib (Llave de chorro)

The valve on the left is a 3/4-inch full-port ball valve for a hose bib. The valve on the right is a 3/4-inch constricted ball valve for a hose bib.

Full port snub valves or bent nose garden valves are available.
I like to use a snub nose/bent nose with 1″ interior diameter base/inlet and a 3/4″ outlet with hose bib threads in gardens and landscapes. I then use the widest-diameter drinking-water-approved garden hoses I can get.

Arrowhead brass products (made in Los Angeles, CA, USA)
1 FIP x 3/4 hose, Hose – bent nose garden valve
930, 90043 00930
NOTE: In the same store (Bimsco hardware in Tucson) I have found this brand and model of valve made as both a full port valve, and a constricted valve, so always visually inspect all your valves to make sure they are what you want.

Two identically labeled Arrowhead brass products 1 inch (inlet) x 3/4 inch (outlet with garden-hose threads) bent nose garden valves. The one on the left is a full port valve (3/4 inch). The one on the right is a constricted valve. ALWAYS INSPECT YOUR VALVES BEFORE PURCHASE TO MAKE SURE YOU GET WHAT YOU WANT.

Mueller (made in China)
Bent nose garden valve (Salida inclinada valvula de jardin)
1 inch: 108-105
3/4 inch: 108-104

Legend is another brand, but more expensive.


Ball Valves
These are great in warm climates, but they can rupture and leak if they freeze in cold climates.

A brass ball valve with hole rupture after freezing.

NOTE: If you live in the USA, and want to support your national economy, plus qualify for the Living Building Challenge prerequisite 14 – Appropriate Sourcing (which sets limits to the distance from which materials can be imported in order to encourage and enable place-based solutions and contribute to the expansion of a regional economy rooted in sustainable practices, products and services), make sure you buy valves made in the USA only.

Do you have an addition to this list? Let me know.

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