About flow and filtering

It wasn’t pretty or long lasting, but our system in from the early days got the water from the downspout into the rain barrels and got it filtered along the way.

I am now looking for a more permanent and slightly more elegant solution. The plumbing part seems straightforward; the filtering, not so much.

As mentioned in the last post, it is not that difficult to find a number of downspout diverters that would get the rainwater into your rain barrels. The good ones come with a built in, self cleaning filter that keeps debris out of the barrels. The even better ones also come with a winter bypass option.

Yet, none of the diverter-filter combos for sale would fit our five inch, round downspout. And if you live in the City of Chicago, you may share my dilemma! It was time again for some DIY. I cobbled together a diverter-filter combo following the basic principles of the better products that are on the market.


One thing to remember is that water likes to cling to the wall of your downspouts. That is where you find most of the flow. Once in the filter, it runs across an angled screen. Most debris should wash across the screen and continue down the downspout. Clean water, on the other hand, passes through the screen and is diverted into the rain barrel.

From concept to creation

I got myself some PVC pipe and fittings in the hope that the concept would translate into a functioning creation.


Looking into the diverter from the top, the angled screen is visible. It starts at a six inch diameter and narrows down to a four inch diameter, where it is attached to the outflow pipe.

rain-barrels-06 rain-barrels-07

Looking into the diverter from the bottom, the four inch outflow pipe and the four to six inch reducer are visible. The outflow pipe extends beyond the reducer into the six inch diverter pipe. That is where the filtered water is collected.


On the side, just atop the reducer, is a two inch pipe connection that leads to the rain barrels. It will convey all the water that passes through the screen and is collected between the four inch outflow and six inch diverter.


And for those who are interested, here is my shopping list for the diverter-filter combo:

  • Six inch schedule 40 pvc pipe
  • Two six inch schedule 40 pvc couplings
  • One six-to-four inch schedule 40 pvc reducer
  • Four inch schedule 40 pvc pipe
  • Two inch schedule 40 pvc pipe plus fittings
  • Some pvc cement and some hardware
  • Stainless steel or aluminum screen
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About Marcus de la fleur

Marcus is a Registered Landscape Architect with a horticultural degree from the School of Horticulture at the Royal Botanic Gardens, Kew, and a Masters in Landscape Architecture from the University of Sheffield, UK. He developed a landscape based sustainable pilot project at 168 Elm Ave. in 2002, and has expanded his skill set to building science. Starting in 2009, Marcus applied the newly acquired expertise to the deep energy retrofit of his 100+ year old home in Chicago.

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