Interesting water barrel/ science problem

[ManglerYJ]

As part of my frugal ways, we have built a rain collection system for our gardens to keep from having to use hose water. I built a stand that holds two 55 gallon barrels on their sides with the inlet/outlets stacked up so that the upper most hole acts as a vent/overflow which drains to the ground, the lower hole from the upper barrel is connected via a pipe to the upper hole on the lower barrel, then the lowest hole is the outlet faucet. Top barrel fills first, to the lower hole and then fills bottom barrel. Once full, the top barrel fills. This works pretty well until I go to use it heavily. An airgap develops between the two barrels to the point that the flow will stop. I drilled a small hole above the higher hole in the bottom barrel which allowed air to come in and the water displaced and moved to the bottom barrel. When water started coming out the hole, I plugged it with a screw and everything works again unless I use a lot again. Then have to vent again.

Any idea why this is happening? Any suggestions as to how to fix it (better than my redneck engineering)?

 

[Keith1138]

I would think the air isn't able to over come the pressure of the water to escape to the upper barrel to vent. This would especially occur if the pipes came out at a 90 and into the other at a 90. Assuming the air is entering through the out flow. I would try attaching a pipe to the top of the bottom barrel to the top of the upper barrel. This way air has a way to escape easier. Do you have any pictures of the set up?

 

[zuke]

You need a vent in the bottom barrel with an outlet above the water level in the upper barrel, put a fitting in the hole you're using the screw in right now, and run a rubber hose up to the top height of the other barrel. Or you could use an upside down pvc j-pipe if it isn't vulnerable where you have the barrels setup. Outlet still has to be higher than the water level in the barrels either way.