Urban gardens
In Philadelphia the rainwater problem is a roof problem: a rowhouse roof sheds a lot of water in a short storm, and a garden on the block can use every gallon. One 275 gallon tote at the foot of a downspout is the usual answer.
01A gardener’s numbers
An 800 square foot roof sends about 480 gallons into a one-inch storm, using the figure of 0.6 gallons per square foot per inch. A single tote holds 275 gallons, so it fills in the first half of the storm and the rest is overflow. That is why the downspout arithmetic comes first and the tote second.
A full tote weighs more than a ton before the plastic and the cage, so the stand needs a firm, level base. A paver pad and a raised stand are common, and a garden bed beside the tote can take the overflow.
02Who asks, and what they ask for
- Community gardens, who want one or two totes with a food-safe or plain-water past.
- Rowhouse owners, who want one tote and advice on the downspout.
- Schools and churches with a bed and a downspout.
- Urban farms building aquaponics systems, who want a documented food-safe history.
03City constraints
Philadelphia’s Rain Check program and combined sewers make rainwater capture a local topic, and the city’s rules apply. The desk gives no advice about permits, and a gardener should ask the city first.
04Where the totes come from
Northeast Philadelphia food makers, the Navy Yard’s tenants and the Camden food plants across the bridge are the closest sources. The desk usually finds a match inside ten miles.
05Post the ticket
?Questions on this page
How many gallons does a rowhouse roof catch?
About 0.6 gallons per square foot per inch of rain. An 800 square foot roof is roughly 480 gallons in a one-inch storm.
Is stored rain safe to drink?
No. Roof runoff is for watering plants only.