Harvesting Rainwater

We get a lot of rain in Costa Rica. At the closest weather station (in Barva, about two and a half miles away) the average annual rainfall is 95 inches. That's almost double what we got back in Clemson, South Carolina. Ironically, even with all this rain, there frequently are water shortages. This is because: (1) the public water infrastructure is so poor (there is a lot of leakage, and they always seem to be repairing the pipes), and (2)  the Pacific side of Costa Rica has a fairly severe annual dry season, that lasts about 5 months.

I became interested in harvesting rainwater when I lived in South Carolina. This was due to the high cost of water, and because I am always interested in learning about new ways to conserve natural resources, whether it be energy, food, or water. I did a little research on rainwater harvesting and discovered that if it was for the purpose of household use, including drinking water (what is called "potable" water), it was fairly complex. But if it was for something like watering a garden, it could be fairly simple. As an experiment, I rigged up a downspout to pipe water from one of our roof gutters into our fish pond. When we got rain it helped refresh the water in the pond, and to keep it full without having to add city water. That's as far as I got.

When we moved here I decided to take it a step further. I wanted to pipe water into our water garden and for watering our plants. Water is inexpensive here, but just the same, it seemed a shame to let all of the rainwater runoff down the hill, when I could put it to good use in the garden. In addition, we have a large cement driveway which collects a lot of rainwater, which has the potential to run down into our neighbors property and cause problems. So, when I decided to build the pond, I figured it would be a good idea to build a water harvesting system first.

I hired a local builder, Alexis Sanches, to build the system. He is an experienced builder and has some experience with building ponds. He and I went to a water tank place out on the autopista between San Jose and Limon. I knew from the start that I wanted a fairly big tank. We settled on a big blue plastic one that held 4,200-liters (1,100-gallons). It came out cheaper per gallon than the the smaller tanks, and the larger tanks would be perhaps too much of a chore to bury. Eleven hundred gallons is a lot of water. Our 4-person hot tub back in Clemson held 316 gallons. So this was about four times as big. The tank dwarfed the pickup truck that we hauled it in. Just before we got to the tank place we noticed a police checkpoint on the highway, so to avoid any difficulty once we had the tank on the back of the pickup, we got off on a side-road and took the back way home.

The tank arrives

The tank created quite a sensation when it arrived. The neighbors wanted to know first, why I was buying a water tank when the city already provided water, and second, why I was buying such a big tank. They thought it would take forever to fill. I told them it was actually quite small for what I planned to use it for, and that with the roof, the driveway, and the average rainfall we had, I could potentially collect 150,000 gallons a year. Now, that's a LOT of water. I don't think they, or don Alexis, believed me.

Digging the tank and drainpipe hole

Alexis and I discussed the options of having a backhoe dig the hole, or having Alexis and a couple of helpers dig it. Alexis convinced me that digging the hole by hand would be cheaper and would cause less damage to the property than a backhoe, even though it would take a little longer. So, they started digging, and two and a half days later they finished the hole. Alexis put sand in the bottom to prevent a puncture from any sharp rocks. On the third day I was taking a nap when I was awakened by a loud WUUUUMP. They had dropped the tank into the hole. Don Alexis hooked up a drain system from the driveway and the small roof over our carport. He then put an electric submersible pump in the bottom of the tank. When he left that Saturday afternoon he predicted it would take several weeks to fill. "Not that long," I said. He smiled.

We got some heavy rain over the weekend. When he returned on Monday morning I said, "Alexis, why don't you check the water level in the tank." He looked at me kind of funny and then walked over to the tank and lifted the lid. He almost fell over backwards in shock. It was already full to the top, all 1,100 gallons of it.

So, now we have the storage tank and a collection system in place. This is just the beginning of the process. I'll report back later on how the project is going.

Happy gardening!