Water, part 1 (Introduction and pre-filter)

WATER, the single most important necessity in life. With modern convenience however it is the most overlooked requirement for living.

For the last year, I have simply used a 5 gallon jug of water with a hand pump. It is time however that I begin installing a more permanent water supply with greater capacity. As I stater earlier, during construction I installed a pipe in to the wall to bring in water from an external source. The original plan was simply to connect a hose from the house to fill a tank.

The more I thought about this however, the more I wished to make a more versatile water system. As I have lived and worked with the box, I have developed a desire to have the unit self contained. This goes back to the "portability" advantage of working with a container. The "easy" way is simply to continue with my original plan and use the house as my water source. This will require though a constant source of potable water being brought in to the box wherever it may be located. Not a very good plan if I should decide to move it to some sort of "unimproved ground".

With this in mind, I have decided to build the system with the ability to handle water from almost any source. My "ideal" would be to pump water from the source (be it a pond or stream) in to a wheeled tank and then bring it to the box for treatment and storage. Using this method and this type of water source can be dangerous to your health!!!! I personally have had food poisoning once in my life 30 years ago. I still remember it clearly and do not ever want to go through it again! It is from this perspective that I design my system.

There are multiple issues at play here and all must be addressed in any system such as this. The issues are as follows:

• Chemical contamination
• Solids removal
• Bacterial contamination
• Removal of larger organisms

Some of these are not a big issue depending on the end use of the water. Because of this I have divided my needs between "general purpose" water (washing, cleaning, toilet usage) and potable water (drinking cooking). In both "types" of water the "general" requirements are the same as outlined above. Drinking and cooking water however are a "take no chances" affair. This water MUST be as pure as humanly possible. 

So, with all of the above we begin to design the system. Course filtering and chemical separation are first up. This is the only thing I built rather than bought off-the-shelf. What I wanted was a filter able to be "renewed" with natural available materials. I also wanted it to function so that lighter contaminants would stay on top of the incoming water and the heavier contaminants would settle to the bottom. The end goal is to have relatively "clear" water exit the prefilter. 

Prefilter construction

I built the prefilter from PVC pipe. It is designed so that water has to travel down through a filter medium before returning back up to the exit. The less flow through this filter, the more likely light chemicals and contaminants will simply float at the top of the of the filter. At the same time the heavier contaminants will settle to the bottom. I started with the following pieses of pipe and fittings

What you see here are all of the pieces prior to assembly. The assembly itself is simply a "pipe within a pipe". For this version I have a 3" outer and 2" inner pipe. There are only 2 modifications that have to be done besides gluing everything together.

The bottom of the inner pipe needs to have slits cut in it to allow the water to flow through. For this I used a saw blade on the vibrating tool seen also in the picture. Once this is complete, the end cap can be glued to this pipe. I was lucky with my cap in that there was a ring molded in to it that came pretty close to centering the pipe in the 3" cap. Note, it is imperative that the end of this pipe be cut square! If it is not, then this pipe will tilt and final assembly become very difficult.

The next and last modification is the hardest part of the whole project. The collar to support the inner and outer pipe together must be modified so that it will slip down the length of the inner pipe.

Looking inside you can see the "lip" that prevents the inner pipe from going all the way through. This lip must be removed. Care must be taken though not to cut too much out of the wall of the fitting or to damage either of the bores where the pipe will be cemented. I actually had a lthe where I could remove this ring. You could however use a Dremel tool, file, die grinder or any other method you should choose. Keep a short section of the pipe that will pass through here to test fit as you go.

Here is the end result looking from the 3" end. The 2" pipe will now pass completely through.

From here, I first glued the 3" outer pipe in to the cap that the 2" pipe was already cemented to. The next step is to cement up the "T" with its fittings for the outlet. The choice is yours if you wish to put the reducer on at this point (I did). Now it is a good idea to have a section of 3" pipe cut and ready to drive the assembly down the 2" pipe with a mallet. Drive it down to where it just begins to make contact with the 3" pipe. Now put cement around the 3" pipe and drive it the rest of the way down.

As long as there is no pressure on the outlet side, it is not really imperative to cement the 2" pipe in the adapter. In a non pressurized delivery system, the collar serves the purpose of "supporting" the inner pipe more than it does sealing it. however if you wish to have the outlet side under pressure, simply measure the offset between where the inner and outer pipe will come to rest when assembled. Apply the cement and then drive it home. This should allow you to operate the whole thing under pressure on both inlet and outlet.

Here you see the finished product. The last PVC fitting to be installed is the threaded connector on the end of the 2" pipe. I want to add that I used a 2" threaded coupling so that the whole thing can be easily filled and emptied. To put it under pressure you will need to make some sort of adapter to screw in to this 2" coupling.

I made this so that I could attach a garden hose for testing purposes. The brass fitting is screwed in to a 3/4 pipe adapter.

On my first trial, I put a layer of course gravel in until it was above the slits I had cut in the inner pipe. I then filled it the rest of the way with general purpose sand from Home Depot. In testing I found that at household pressure and a 2" column of sand, I was flowing approximately 1/2 gallon per minute. For my needs, this is far too little.I however replaced the sand with gravel all the way to the top. At that point, it flowed as fast as I could fill it and would even work under gravity. In the coming days I will experiment further with filler material.

Please keep in mind my intention with this. Its purpose is simply for pretreatment and to remove some solids, scum and oils. It is not intended to produce drinking water! Its purpose is to get more life out of the "higher end" filters down the line and keep sediment out of your holding tank.

In the next installment I will move on to the holding tank.