A lot of cities push rain barrels as a way to save water and reduce flooding. Our water comes from the Detroit and returns to it as sewage, so I’m not sure there is any water saving, but there is a small cash saving (very small) if you buy 30 to 55 gallon barrels from the city and connect them to the end of your drain spout. The rainwater you collect won’t be pure enough to drink, or safe for bathing, but you can use it to water your lawn and garden. This sounds OK, even patriotic, until you do the math, or the plumbing, or until you consider the wood-chip alternative.

The barrels are not cheap, even when subsidized they cost about $100 each. Add to this the cost and difficulty of setting up the collection system and the distribution hose. Water from your rain barrel will not flow through a normal nozzle as there is hardly any pressure. Expect watering to take a lot longer than you are used to.

In Michigan you can not leave the water in your barrel over the winter, the water will freeze and the barrel will crack. You have to drain the tank completely every fall, an almost impossible task, and the tank is attached to a rainspout and the last bit of water is hard to get out. Still, you have to do it, or the barrel will crack. And the savings for all this is minimal. During a rainy month, you don’t need this water. During a dry month, there is no water to use. Even at the best, the The marginal cost of water in our town is less than 1¢ per gallon. For all the work and cost to set up, two complete 40 gallon tanks (like those shown) will give you at most about 70 usable gallons. That’s to say, almost 70¢ per full filling.

How much lawn can you water? Assume you like to water your lawn to the equivalent of 1″ of rain per week, your 70 gallons will water about 154 ft² of lawn or garden, virtually nothing compared to the typical Michigan 2000 ft² lawn. You’ll still have to get most of your water from the city’s main. All that work, for so little benefit.

A far better option is wood chips. They don’t cover a lawn, but they’re great for shrubs, trees or a garden. Wood chips are easy to spread, and they stop weeds and hold water. The photo at left shows a wood chips around the shrubs, and a particularly poor use of wood chips around the trees. For shrubs, trees, or a garden, I suggest you put down 1 to 2 inches of wood chips. Surround a young tree at that depth to the diameter of the branches. Do not build a “chip volcano,” as this lazy landscaper has done.

Consider that, covering 500 ft² of area to a depth of 1.5 inches will take about 60 cubic feet of wood chips. That will cost about $35 dollars at the local Home Depot. This is enough to hold about 1.25″ or rainwater, That’s about 100 ft³ or water or 800 gallons. The chips prevent excess evaporation while preventing weeds and slowly releasing the water to your garden. You do no work. The chips take almost no work to spread, and will keep on working for years, with no fear of frost-damage. A as the chips stop working, they biocompost slowly into fertilizer. That’s a win.

There is a worst option too, called a rain garden. This is often pushed by environmental-gooders. You dig a hole near your downspout, perhaps ten feet in diameter, by two feet deep, and plant native grasses (weeds). When it rains, the hole fills with water creating a mini wetland that will soon smell like the swamp that it is. If you are not lucky, the water will find a way to leak into your basement. If that’s your problem look here. If you are luckier, your mini-swamp will become the home of mosquitos, frogs, and snakes. The plants will grow, then die, and rot, and look awful. It is very hard to maintain native grasses. That’s why people drain swamps and grow trees or turf or vegetables. If you want to see a well-maintained rain garden, they have two on the campus of Lawrence Tech. A wetland isn’t bad, but you want drainage, Make a bioswale or muir.

Robert Buxbaum, May 31, 2023. I ran for water commissioner some years back.