Full-port valves give you the best water flow (and most joy) with gravity-fed rainwater tank systems
Full-port valves do NOT constrict and reduce water flow, whereas most conventional valves DO constrict and reduce water flow—especially when used in the context of low-pressure gravity-fed rainwater systems. And the lower the level of the water in your tank, the lower the pressure.
Using a conventional constrictive valve will result in frustration when water dripples out of your tank when the water level is low.
Whereas using a full-port valve will result in joy as water flows at a good pace out of your tank—even when the water level is low.
For more info see the video below….
The demo I feature in the video was designed and made by Lincoln Perino.
For more on these full-port valves, where to get them, and ideally-sized garden hoses and pipe see here.