Most of us would not try to fill a glass of water, or any container for that matter, by forcing it in the bottom.

Why, then, do we insist that your rain bench be bottom-filled?  Hopefully  this post will explain that…

Numero Uno:  Most important is the concept of pressure release.  Yes, I learned this the hard way.

Picture a ridiculously heavy downpour.  Water is flowing in so fast from your downspout diverter to your bench that air cannot flow back up the line. 

In my case, I was testing it and when I shut off the hose —  **Ppfwoooooshh** — air and water shot out the top of the rain diverter like Old Faithful – or my favorite, the Lone Star geyser…

So, other than that, why else fill from the bottom?

Well, a number of reasons, but first you may be saying,”that’ll never work– it’ll just back up and overflow.”  true…

…it’ll overflow either your upper rain bench fitting or your downspout diverter, whichever is lower.  I won’t get too involved, but check out NASA’s explanation of Pascal’s Law to learn more.

so how about those ‘number of reasons?

  1. place your rain bench or water tank anywhere and bury the line, now you don’t have to put it right at your downspout
  2. every time it rains, fresh water is added and old water flushed out.  {vs. filling up a barrel and then not being able to add at all, because the top inlet is blocked.}
  3. connect multiple benches together and fill all at once, increasing your capacity to unlimited — just set all overflow fittings at the same height
  4. you have a pressurized line anywhere from your downspout to your bench.   run a soaker, install a hose bib or add a water level indicator