Construction Method for a 5 cubic metre Ferro-cement Pumpkin Shaped Aboveground RWH Tank

Home / Construction Method for a 5 cubic metre Ferro-cement Pumpkin Shaped Aboveground RWH Tank

1	Choose a suitable site. The site should be - Close to the house - Firm ground - Not obstruct future constructions
2	Dig a pit in the ground with depth and width according to the size of the tank you are planning to make. The diameter of the hole should be half a metre bigger than the diameter of the tank.
3	For the foundation of the base draw a circle of radius 840 mm (2'9") on the ground and dig to a depth of 100 mm (4").
4	From the centre of the circle cut a drain of width 150 mm and depth of 150 mm to the outside (as in the picture).
5	Lay PVC pipe of 50 mm (1 1/2") diameter on the drain for outlet and washout. On the centre fix a 50 mm (1 1/2") PVC pipe length of 100 mm (4") with an elbow joint to be above the concrete base. concrete
6	Cover the base with concrete mixture 1:2:4 for a depth of 65 mm (2 1/2"), fixing the pipes firmly to the ground.
7	Cut 4 length of 2440 mm (8") of chicken wire and lay them across each other over the base as in photo.
8	Place and fix with glue and strip of PVC around the outlet pipe as in photo.
9	Place 10 bolts (65 mm), head down, equal distances around the concrete base by measurement. Fill the base with rest of the concrete to a depth of 40 mm (1 1/2"). Leave the base to dry for 1 day.
10	Fix one end of each leg of the frame to the bolt on the base with the nut and other end to the ring. With the aid of nearby structures, straighten the frame. Fix all ten legs in the same way.
11	To establish the pumpkin shape, by tying 6 mm wire around the structure vertically, allowing 100 mm gap between the two wires.
12	Cut 8 pieces of chicken wire of length 2300 mm (7") and cut them diagonally.
13	Lay the chicken wire vertically outside the structure and tie it to the 6 mm bars on the frame. Chicken wire should be held firmly to the frame. Lay the next layer of chicken wire on top of the first so the octagonal spaces overlap each other and tie to the frame as before. To make the filter role the chicken wire of desired length to 300 mm (12") width and fix it to the mesh.
14	Apply first layer of cement of 1:3 mixture from outside of the mesh to a thickness of 12 mm (1/2"). Apply 2nd layer of cement and smooth the outside. The total thickness of the cement layer should not exceed 20 mm ( 3/4"). It's best if this could be done within one day. Cover the structure with wet rags and leave it dry for one day.
15	Make a scaffold over the tank for easy access into the tank. Remove the 6 mm wire and the frame legs from inside the tank and apply 20 mm (3/4") thickness cement layer 1:3 inside of the tank. Water proofing additive should also be applied to this mixture and smoothened.
16	Cement the base of the tank to 300 mm (12") height and 25 mm (1") thickness.
17	Cement the mouth of the tank 75 mm (3") height and 40 mm (1 1/2") depth in order to place the lid. Place a 6 mm wire around the edge to strengthen it further.
18	Cover the filter with cement inside and outside as in picture. Lid of the tank can also made from ferro-cement.
19	Leave the tank to cure for at least 14 days after completion. After 6 days of completion fill the tank slowly 1 foot at a time. Make sure the tank is not kept dry.
20	Cross section of a tank
	Frame
	Special equipment needed

Material for 5 cubic metre Ferro-cement Rain Water Harvesting Tank

Items	Number	Unit
For the Tank
3/4 concrete metal stone	0.2	m²
Sand	1.7	m²
Cement	450	kg
Chicken Wire (24")	40	m
Binding Wire	1	kg
Padlo Cement - 0.5 kb @ 100	0.5	kg
Bold nuts	10	5/8" x 2 1/2"
For Reusable Frame
G.I. for legs as in diagram 1	10
6 mm wire	25	kg
PVC pipes
50 mm down pipe 1	1
50 mm PVC elbow	1
50 mm PVC valve socket	1
50 mm PVC end cap	1
50 mm x 20 mm reducing T	1
20 mm PVC valve socket	1
20 mm tap	1