Here is just one way to modify your existing rain bench to make the cap itself collect rainwater and put it inside your bench….

 RainBench Retrofit:

Collect water that falls on your rain bench, too.

*This retrofit isScreen Shot 2015-03-24 at 10.00.33 PM for standard 65 gallon Rain Bench made with 1 DIY kit, 1 sheet of plywood and some 2x2s…

1.  First, pick up a 1 1/2″ street elbow like this..  ($1.80 at Home Depot)

Screen Shot 2015-03-24 at 10.00.47 PM2. Insert the large end into the 2 inch top threaded fitting of your liner

3.  Pick up a couple of 8’ pieces of 1×3 furring strips ($1.07 ea at Home Depot),  although 1×4 or 2x4s would work too. I just used some pieces of scrap lumber I had laying around the shop.

4.  Cut two pieces at 28 inches long and two pieces at 40 inches

Screen Shot 2015-03-24 at 10.01.17 PM(The angles shown are because that’s what one end of the scrap lumber was like already, and I’m just lazy 🙂

(I used an old rain bench because it was handy and the new retrofit shows better — ok that’s really more justification for active laziness…)

Screen Shot 2015-03-24 at 10.01.36 PM5. Drill a 2″ hole in thScreen Shot 2015-03-24 at 10.01.29 PMe center of one of the 28″ pieces

(2″ hole saw:  $7.49 at Home Depot)

(nope, I am not paid by Home Depot)

Screen Shot 2015-03-24 at 10.01.46 PM

6. Shave the top side around the 2″ opening at an angle so that a filter will sit down into it.  Or get a smaller filter  (Again, I used a filter I had here from a self watering planter)

7. Fasten the solid pieces around the perimeter of the cap so the tops are just above the surface of the existing cap, catching the water that falls on it.   Predrill all holes.

Screen Shot 2015-03-24 at 10.01.59 PMScreen Shot 2015-03-24 at 10.02.08 PM

8. Fasten the piece with the hole horizontally so that it fits over the end of the 1 1/2″ street elbow, and place a small kitchen sink strainer in the opening.

Angle this horizontal board slightly back toward the bench, so water backs up and flows into the bench rather than right over the edge.

You can toenail or just support that board like I did below.