Gravity-Fed Water Treatment System


A large comet or asteroid impact will produce high concentrations of acid rainfall and black rain that will contaminate surface water with concentrated acids and heavy metals. Sickness and death will result from drinking this polluted water. Because of the vast damage brought by an impact, municipal water treatment facilities may be damaged and inoperative. Underground aquifer systems may also be knocked out by the impact. The Gravity-Fed Water Treatment System provides high volume treatment and purification to provide drinking water for a small community. The System design is:

* Heavy Duty Capacity: Converts 100,000 gallons of contaminated surface water to drinking water.

* High Rate: Treats approximately 50 gallons of water per hour.

* Operates without electricity.

* Neutralizes concentrated acids.

* Filters contaminants (0.5 microns or larger) and heavy metals from water.

* Kills bacteria and renders water microbiologically safe.


Construction Details (Refer to Parts Lists and to Photographs)

{Water Filter - Drum Side}



Water Filter - Filter End



* Drill a one-inch hole at the base of one 55-gallon plastic drum, approximately 5" from the bottom. Compare drill bit with PVC Connectors prior to drilling to insure proper hole size.

* Using Multi-Purpose (PVC, CPVC, ABS) Cement join the 1" PVC D-2466 (1" Female Pipe to 1" Male Thread) connector to the 1" PVC Male-to-Male Coupler, to a 1" PVC D-2466 connector. To cement the connections, apply cement to both sides of the connection, push the joint together and give them a small twist. Allow the cement to cure for 4 hours prior to use.

* Insert the PVC Assembly into the 55-gallon drum. If required, use a round file on the drum to increase the size of the hole slightly to allow the assembly to slide into the hole. Clean out plastic filings from the inside of the drum.

* Slide the brass washers onto the PVC Assembly. If required, use a small round file on the washers to increase the size of the inside hole to allow it to slide onto the PVC Assembly.

* Coat both sides of one thin brass washer and one rubber washer with a silicon sealant. Place the thin brass washer onto the PVC Assembly. Next place the rubber washer. Insert the PVC Assembly into the 55-gallon drum. On the inside of the drum, insert an untreated rubber washer and a thin brass washer and then an electrical type 1" nut. Tighten the assembly.

* Push a 1" Female Adapter Insert into the PVC SPA-Flex Pipe. This pipe is semi-rigid. Use a rubber mallet to drive the insert into the pipe. Use a metal clamp to secure.

* On the other side of the sixty-foot pipe repeat the above step and drive a Male Adapter Insert into the pipe.

* Next, fabricate the Water Filter Assembly. This will join the two Water Filter Housings with two 1" x 6" Brass Nipples. The assembly is connected as follows: Outlet side of Filter Housing #1 to Nipple #1 to Inlet side of Filter Housing #2. Outlet side of Filter Housing #2 to Nipple #2.

* Insert the 5-micron Filter Cartridge into Water Filter Housing #1 (Drum Side). Insert the 0.5 Micron Carbon Briquette Filter Cartridge into the Water Filter Housing #2 (water outlet side). Follow filter cartridge instructions for installation details. The Water Filter Housings should be lubricated. Clean petroleum jelly is a lubricant that can be used for this purpose.

* Connect female side of Hose Assembly to a 1" x 2" brass nipple to a 1" Ball Valve. Verify proper orientation. The outlet side of the Ball Valve should be connected to the hose assembly. The control valve should move freely once the Ball Valve is connected to the drum. Now, connect the other side of the Ball Valve to the PVC Assembly on the 55-gallon drum. I recommend two persons perform the final step in order to keep the hose assembly from getting twisted or damaged.

* Connect the male side of the Hose Assembly to the inlet side of the Filter Assembly. I recommend two individuals perform this step in order to prevent damage to the Filter Assembly.


Parts List & Supplies


Item (or equivalent)

Unit Price

Total Price


55-Gallon Open Head Plastic Water Drum (Food Grade)

$ 60.97

$ 121.94


Water Filter Housings – American Plumber W10-PR

$ 39.95

$ 79.90


1" x 6" Brass Nipples

$ 7.26

$ 14.52


1" x 2" Brass Nipple

$ 2.35

$ 2.35


1" Ball Valve – Apollo #70-105-01

$ 13.76

$ 13.76


1" PVC NIBCO PVC-1 D1 D-2466 (1" Female Pipe to 1" Male)
One connector should have a high ridge at end of threads for which brass washer must rest against.

$ 0.49

$ 0.98


1" PVC Male-to Male Coupler

$ 0.45

$ 0.45


1" ID Rubber Washer

$ 1.00

$ 2.00


1" ID Thin Brass Washers

$ 1.00

$ 2.00


Electrical Type 1" Nut

$ 0.20

$ 0.20


1" PVC I NSF Female Adapter Insert

$ 1.26

$ 1.26


1" PVC I NSF Male Adapter Insert

$ 0.38

$ 0.38

60 Feet

1" ID PVC SPA-Flex Pipe

$ 1.97/ft

$ 118.20


¾" to 1 ½" Clamps

$ 0.59

$ 1.18

40 Yards

100% Bleached Cotton Cheese Cloth (36" wide)


$ 32.00


5 Micron Filter Cartridges – American Plumber Model W5CPHD

$ 10.63

$ 212.60


0.5 Micron Carbon Briquette - American Plumber
Model W.5CBHD

$ 38.79

$ 775.80


Filter Wrench – American Plumber Model WWHD

$ 4.83

$ 9.66

200 lbs

Baking Soda (Arm & Hammer)


$ 79.60

26 gallons

Clorox Bleach (Unscented)


$ 43.03


Portable pH Meter

$ 160.00



Hand Operated Water Pump Stroke – Rieke Corp MR50XL

$ 19.00

$ 19.00




$ 1,690.81


Filter System Operations

* The Gravity Fed-Water Treatment System consists of a 55-gallon drum for acid neutralization, a filter assembly to remove contaminants, and a second 55-gallon drum for bacterial treatment.

* Close the ball valve on the acid neutralization drum.

* Fill the drum with water. Pass the water through Cotton Cheese Cloth to remove large contaminants (such as leaves and twigs) as you pour the water into the drum. Cheese Cloth can be obtained from a fabric store.

* Once the drum is full, treat water with Baking Soda to neutralize acidity. Check acidity using pH meter or litmus strips.

* The Filter Assembly should use a 1" Inside Diameter (ID) hose that is a minimum of 60 feet long. The gravity fed system requires a minimum head pressure to operate effectively. Using a shorter hose length or a smaller diameter hose will defeat this system.

* The acid neutralization drum should be placed at the top of a hill and the filter assembly must be placed at the bottom. The hill should have a 20-degree incline or steeper, in order for the system to work effectively.

* After the water has been neutralized for acidity, open the ball valve and check for leaks. Tighten connections. Allow water to flow for 5-6 minutes before using the system for the first time. The second filter contains carbon fines (very fine black powder) that need to be flushed from the system.

* Once the system has been flushed, the water should be collected into the second 55-gallon drum (or other containers). This water should be treated with chlorine to kill bacteria and disinfect the water to make it microbiologically safe. Approximately 11 teaspoons of unscented Clorox Bleach will disinfect a 55-gallon drum of water.

* The Water Purification System will require periodic maintenance. Filters will need to be removed and cleaned or replaced. Most of the contamination will be concentrated in the first filter assembly containing the 5-micron filter.

(If the precipitate from the acid neutralization process clogs the filter assembly too quickly, it may be necessary to perform the acid neutralization process in another container and pour the neutralized water through cheese cloth to filter out these precipitates first.)