Cistern Cleaning

It’s been a few years since the cistern was installed and now that I have completed the plumbing, I decided that this was a good time to clean it. It hadn’t gotten a whole lot of use as of yet considering the well has been the primary source of water for mixing mortar. I was quite curious as to what I might find. One of the screens that I had inserted into the downspout had gotten badly bent causing leaf debris to enter the rain catchment system. I knew that I would find some leaves in the cistern, but what else might I find?

Using a trash pump, the cistern was drained within an hour except for the last inch or so. Gingerly, I removed the manhole cover to reveal the contents inside. There was no odor to speak of and not too much else besides water: no mice, no rats, nor worms—not even Elvis nor the Loch Ness Monster. The few inches of water that remained was crystal clear with only a little silt down at the bottom of the tank. As I entered the tank, I did come across my nemesis—there were two dead Asian ladybugs.

Using a wet/dry shop vacuum, I sucked up the remaining water, leaves and silt. (The tank is big enough for me to walk around inside.) I scrubbed the walls and bottom of the tank a chlorine solution and then rinsed the walls a couple of times.

After a cold winter, the concrete tank showed no signs of stress. I was a bit concerned about this considering the tank had partially frozen. It’s was only a couple of weeks ago that there was still ice floating in the tank and during the months of January and February the upper part of the tank was frozen solid. I became a bit concerned during those months when water started back-flowing through the cistern pipe inside the house. It wasn’t a lot of water, but eventually the drips became gallons of water! I attributed this strange occurrence to the expansion of the ice inside the cistern pushing the water out through the bottom of the tank. This coming winter I will throw a bunch of straw on top of the ground around the cistern in an attempt to keep the cistern from freezing.

New Screens
Since I now had some experience under my belt with harvesting rainwater, I decided to make a few improvements to the system. The connection between the downspouts and PVC pipe was completely changed and new screens installed. For $3.55 (each), I purchased two flour sifters and the local Walmart and pulled the stainless steel screening out of the sifters. The dome shaped screen fit perfectly inside of the 4″ pipe connection located under each downspout. This should take care of the leaf problem, but just in case, a second much finer screen was installed directly before the water enters into the cistern.

Using a cat litter bucket, (yes, I know it sounds bad but it just held kitty litter) I cut a 4″ hole in the bottom of it and installed a toilet flange. I made a rubber gasket to prevent leaks and used stainless steel screws to attach it to the bottom of the bucket. The 4″ toilet flange was slightly smaller than a standard 4″ pipe, and fit inside of the 4″ vertical cistern pipe.

Another great find besides the flour sifter was a grease splatter screen. This beauty was almost the same diameter as the bucket opening. Not only was the size right, but it is a super-fine, stainless steel mesh. The screen is mounted to the top of the bucket using four pieces of insulated telephone wire—just enough to keep it firmly on the top of the bucket.

New Roof Washer
Besides the new screens, I decided to modify the roof washer. A roof washer collects the initial rainwater off the roof and diverts it to a holding tank. The purpose of this is to prevent any dirt and debri from entering the cistern that might have been collecting on the roof since the last rain.

There are commercial roof washers available on the market from Australia that do this automatically, but I found them to be rather expensive and I wasn’t convinced they would hold up to the stress of Midwestern winters. Instead, I purchased a 4″ knife valve typically used on fish farms to divert water flow. The valve costs approximately $60—less than half of cost of the fancy roof washer from Australia. It’s attached to the bottom of the holding tank and after a rain, the valve is opened to discharge the water held in the tank. In all fairness, it is a manual process compared to the automatic valve found in the Australian system. I don’t see this as a major drawback considering I am at the house every week. During the winter months, the valve is left open to allow any roof water to flow out and away from the house using a series of pipes.

New Rain
I assumed that once I installed the new roof washer and filter system that it wouldn’t rain for months. I figured I jinxed the whole Midwest into a prolonged drought, but I was wrong. By Wednesday morning it was raining and I got to see the system in action. I was amazed by how well the grease splash screen worked. This very finely meshed screen was catching tree pollen that floated out of the top of the roof washer and into the main flow of water to the cistern. Granted, this screen won’t catch the extremely fine particles of dirt, but I am quite certain that the 30 micron and 5 micron water filters will last a lot longer filtering rain water vs. well water. Once I get enough water collected in the cistern, I will have it tested and share the results here on the web site.

That’s about it for this week.

A Chipping Sparrow sings his sing high atop a cedar.