Rainwater
El Salvador has two seasons: wet and dry. The dry season is wonderfully sunny with bright blue skies. It's great for going to the beach or drying your clothes in the sun, but there is no rain and the landscape slowly shifts toward brown as the months go by. The rainy season is, well, rainy. Most every afternoon and evening you can expect rain. The floors are constantly being mopped, everything is wet and moist, and the mold and mildew thrive. Drying clothes becomes more of a challenge as you fight the clouds for sunlight and try to dodge the rains.
Our home in El Salvador is up on a mountain of sorts in a town called Los Planes de Renderos. We live just far enough on the outskirts of town to be out of reach for city water. It wouldn't be drinkable water, but it would be fine for washing dishes, taking showers, and flushing toilets. Since the water won't come to us, we have to bring it to the house. Every two days a large truck arrives with 8 cubic meters of water and partially fills our two cisterns. It's expensive. So as the rainy season approached last spring, we made plans to start catching some of the free water that would be falling from the sky on an almost daily basis. Additionally, the rains would force us to make greater use our electric clothes dryer, which meant a higher electric bill. We hoped to offset the increase in our electric bill with a decrease in our water bill. That was the plan anyway.
Rain water collection is fairly straightforward. Collect the runoff from a clean surface like a roof or watershed and pipe it into a tank. Nature and gravity do most of the work. You can make it fancy with multiple tanks, first-flush filters, and other enhancements, but we aimed to keep it simple to start.
The roof of the house is flat, which makes it a great place to run clothes lines, but a lousy place to collect water. All the water from the roof flows to a corner drain, down through a concrete wall and then out to the street. There's no place to intercept the water while it is still higher than either of our cisterns. It's also rather dirty since it's running straight off the flat roof.
The house has two cisterns. One is on the top floor, and one is on the ground floor at street level. The top cistern is accessible from the roof through a hatch in the floor. When the water trucks come, we pull a hose up to the roof, pop the hatch and fill it up. If we could catch water up on the roof, we could pipe it directly into this cistern. Once that cistern is full, turning a couple of valves moves water into the lower cistern. Seemed like a perfect setup.
All we needed was to create some sort of collector for the water. Using the roof itself was out, but the steel railings that ran the perimeter seemed like they might provide a decent structure for building some kind of watershed.
My goal was to build something on a budget without using expensive materials. I thought about buying lumber and corrugated tin sheets and constructing a watershed, but it would have been expensive. Also, I wanted something that would stay out of the way and be easy to take down in the dry season.
So, I did what any modern man would do when faced with such a project: I got on the internet and started searching for ideas and designs. Most of what I found focused on using existing roofs –something I couldn't do. Since I wanted something temporary, I started thinking about using tarps. However, I couldn't find any information about using tarps in rainwater collection. I figured most people probably weren't looking for temporary systems, and that tarps probably start to deteriorate after awhile and perhaps even leech some chemicals into the run-off. Since we wouldn't be drinking this water – or even be using it to grow food – I wasn't particularly worried about the water quality (at least for now). I figured it couldn't be much worse than what we were getting from the trucks. I had seen things wiggling across the oily surface of the water in our cisterns more than once. It's why I always brushed with bottled water.
With no information on tarps to be found not the internet, I decided I was about to be an innovator. Or an idiot.
The roof is a concrete U lined by steel railings with a section of steel laminate filling in the remainder. I suspect the laminate section was added after the original construction once it was discovered the exposed terrace level below was mostly unusable during the rainy season. The steel railings run around this laminate section providing a sturdy frame on three sides. I figured if I could use this frame, I could save on construction costs. It would also put the collector in a part of the roof that was never used, keeping it out of the way but still high enough to run down into the cistern.
Ultimately, I decided to suspend a sloped tarp between the railings on a series of wires using the eyelets installed on the tarp's corners and edges. I would use turnbuckles to tighten the wire and keep the tarp taught. Along the lower edge of the sloped tarp I would install a gutter to collect the run-off and pipe it into the cistern. A simple enough plan. So I headed off to Freund (the local hardware chain) to buy some gutters, PVC, wire, fasteners, turnbuckles, and the largest tarp I could find.
The first step was to mount the gutter to the lowest railing. I drilled the holes on a slight diagonal to ensure the water would flow towards the drain and used zip-ties to hold it in place. Cheap and easy.
Next up was suspending the tarp. This proved to be more difficult than I had anticipated due to the wind. Each gust turned the tarp into a sail, pulling it up in the air. I enlisted the help of some of the kids to hold the tarp down while I ran the wires.
I got the wires as tight as possible and then started using the turnbuckles to add as much tension as I could. (Worth nothing: I was using cheap wire that had no tension rating. I worried each turn would snap the wire and send the ends flying around like a whip.)
After several hours of tightening, retightening and cranking turnbuckles, it looked like I might be finished.
The slope wasn't as severe as I had expected. I didn't realize how much the tarp would sag under its own weight, and I couldn't get everything as tight and secure as I'd like, but I grabbed a bucket of water and hoped for the best.
Drats.
The water collected in the center of the tarp and stayed there. Nothing made it to the gutter. The pitch of the tarp wasn't severe enough to overcome the sag. Frustrated after hours of work, I quickly and somewhat frantically decided to immediately move to Plan B.
I cut the PVC-to-gutter connector apart to create a crude drain. After hours of fighting to keep the tarp from snagging and tearing, I was now going to cut a whole in the center and install a drain. If the water was running to the center, that's where I'd collect it.
It didn't work, the water flowed around the drain as it was still higher than the lowest point of sag. I decided that to fix this I would need to raise the lower end of the tarp to the top railing. This would hopefully provide the necessary pitch to drive all the water to the drain. I also invested in an actual sink drain and a tube of silicon sealant to install it.
While doing this I realized the tarp wasn't holding up well under all the pulling and stretching. The eyelets were starting to pull away from the tarp, some of the wires had snapped, and the sag in the center had gotten worse.
I made an effort to shore up the eyelets wherever I could.
Plan C. Ready.
A initial bucket test showed promise. So I waited for it to rain.
Failure.
Under the force of an actual rainstorm, the tarp continued to sag and left the drain sticking up in the middle with a large pool of water all around it. Water collected in the pool until the weight finally pulled the tarp loose and popped the drain all the way out.
Plan D. I decided to "peak and valley" the front side, hoping to give a little more structure to the tarp along with some needed vertical height. I would reinstall the gutter, and all the water would run out of the valleys.
Once I saw it finished, I didn't even bother with the gutter. It wasn't going to work. The tarp had stretched during the previous attempts and sagged to the roof below. When the wind blew (which often happens when it rains) it flapped like a sheet in the breeze.
Plan E. I was convinced my problem was height, and decided to raise the backside of the collector. The guard and I harvested some bamboo from the empty lot next store. Then Miguel and I put up the equivalent of a make-shift soccer goal.
Taken all together it may be the ugliest thing I have ever built. While my first design may have been a failure, it at least looked impressive. This looked terrible, and worked about the same.
I finally surrendered. Using a tarp was simply not going to work. At least not in this setup. Perhaps this had been why I couldn't find any information on the internet about using tarps. I made a note to share my findings and hopefully prevent some other eager fool from embarking on a similarly doomed project.
I was still, however, determined to collect water.
Plan F. I decided to spend more money and build a proper watershed. Since I could get as much free bamboo as I wanted from the neighboring lot, that meant I would only need to buy the corrugated tin. I started cautiously, only purchasing 3 sheets. I also enlisted the help of a visiting American team to construct this beefier collector.
We reattached the gutter and built a frame for the tin sheets. We did all of this using bamboo and wire, carefully placing our supports over the support beams of the existing steel roof below.
Because we were building on the laminate roof, we couldn't securely attach the support posts. The front and sides were sturdy, but the frame was essentially resting on the roof. This would eventually prove problematic.
The next day, we attached the tin sheets, again with wire.
It looked good, and it seemed sturdy. When it rained, we collected water. I felt like we were finally making some progress.
Encouraged, we decided to expand. We purchased more tin sheets and the frame was extended the full length of the gutter.
We were collecting water, but not nearly as much as we had hoped. We talked about extending the watershed back to double the surface area.
Then, one windy night, we discovered our new design was not so strong after all. Without being attached to the roof, the support posts were easily picked up by the wind and the whole structure was knocked down.
We rebuilt once, but then it happened again. By now, the rainy season was almost over. The ruins of the water collector were being used to dry clothes in the sun.
As slowly as it had been put together, it started to be taken apart. The pile of bamboo, wire and tin sheets were just a reminder of all that had gone wrong. The tarp made it's way downstairs to work as a drop cloth during painting projects. Some of the tin sheets ended up as the roof to a rabbit cage. Much of the bamboo wound up serving as fence posts for the chickens' yard.
The rains will come again in April. This time, perhaps, we will be ready.










































































































