All-Weather Stock Tank

by M.W. Clark, R.L. Ricketts and H.J. Hall
University of Missouri College of Agriculture
Agricultural Extension Service
Circular 523 Columbia, Mo. (First Edition December, 1945)

A well insulated concrete tank has been in use on a Boone county farm for a full year with no trace of ice on the water even in temperature 5 degrees below zero. It is equipped with automatic float valve and trickle overflow pipe, the latter to be used only in freezing weather. The tank gets its water supply by gravity from a large pond.

With such a tank any one of the thousands of good farm ponds in Missouri may be made a dependable year-around means of having water before livestock at all times. This is done without pump, motor, tank heater or labor of cutting ice in winter. The insulation is semi-permanent and covers most of the tank, leaving only 18 inches of the inside of the tank exposed at one end. The cost per year of service is low.

This circular contains a full description of the original tank and tells how to make one like it. The tank holds about 325 gallons of water. About 1 ½ cubic yards of concrete is required to make one by the same plan.

The Original Tank

The first tank of this type was built more than a year ago on a general livestock farm near Columbia. It is located just below a large pond which is filled with the runoff from a grass-covered, fenced watershed. Built originally as a standard open-top tank, it had been in use for some time when the approach of winter suggested to the owner the desirability of insulating it and adding other safeguards against freezing.

With this object in mind, the extension agricultural engineers of the University worked out the plan for insulating the tank and providing a trickle overflow. Assistance was received also from T.A. Ewing, county extension agent of Boone County.

The lowest temperature recorded last winter by the U.S. Weather Bureau at Columbia was 5 degrees below zero. While this is not the coldest weather we can expect in Missouri, or in Boone County, last year’s experience shows that the tank is adequately protected to withstand all but the extremely low temperatures which are very infrequent in this latitude.

After the first hard freezes in early winter the trickle overflow system shown in Figure 12 was put into operation by removing the plug from the 3/8-inch hole in the side of the overflow pipe. This opening is about 1 inch under the water level set by the float adjustment. Through this hole, water ran down the overflow pipe and out through the drain to a convenient distance from the tank. The overflow trickle aids greatly in keeping the temperature of the water in the tank above freezing.

With the small overflow operating all winter the water line in the pond is pulled away slightly from the ice covering the pond. An air space is thus formed between the ice and the water, and from this space fish may obtain oxygen. The air space also forms some insulation and keeps the pond from freezing as deep as it otherwise would. If the overflow trickle were allowed to run through the entire winter, the amount of water drained away through the 3/8-inch port would lower the water level no more than about 1 foot on a ¼-acre pond – even if no rain or snow fell during this period.

Figures 2 and 3 give details of form construction. These forms may be used repeatedly if properly cared for and may be a community project, thereby reducing costs.

How to Build the Tank

The lists of materials required, along with the necessary details of plans, are given in this bulletin.

When the forms are constructed and put together for the first time the corners of the forms and the 2×4 braces should be marked with light saw cuts in such a way that they may be assembled the same each time.

It is very important to give the entire surface of the forms a coat of linseed oil or used crankcase oil before using them each time to help preserve them and keep concrete from sticking to them.

Figures 3 and 4 show top view of assembled forms and concrete tank as poured and before being insulated.

Note the 2×6 and 2×8 whalers. These whalers slip over outside forms to point 6” to 8” from the bottom. They prevent the bottom of outside forms from pushing out and eliminate staking.

Location of Tank:

The tank should be located on a well drained site. When placed below a pond it may be any reasonable distance from the dam but should usually not be closer than 20’ to 30’. The top of the tank should be located at least 4’ to 5’ below the pond spillway in order to obtain maximum use of pond during the dry seasons.

Excavation for Tank:

At tank location excavate an area 4’6’’ x 9’ to a depth of 5” or 6” at the shallower side. The floor of this excavation should be smooth and level. Next, the location of inlet and drain pipes entering the tank should be laid out. Excavate and install these connections at correct elevations. Refill trenches and tamp well, especially that part under tank. See Figure 5.

Only the necessary connections entering the tank need be installed at this time as additional pipe may be added later.

Bill of Materials for Forms:

2 pcs. 2” x 6” x 6’ #2 yellow pine
2 pcs. 2” x 8” x 10’ #2 yellow pine
9 pcs. 2” x 4” x 12’ #2 yellow pine
3 pcs. 2” x 2” x 12’ #2 yellow pine
13 pcs. 1” x 6” x 12’ #2 yellow pine
8 ea. 3/8” x 3 ½” Machine bolts
20 ea. 3/8” x 4” Machine bolts
8 ea. 3/8” x 6 1/2” Machine bolts
4 ea. ¾” x 4” Machine bolts
8 ea. 3/8” wagon-box endgate rod nuts (optional)
64 ea. 3/8” washers
32 ea. ¼” x 4 ½” carriage bolts
4 ea. ¼” x 6” carriage bolts
4 ea. ¼” x 8” carriage bolts
40 ea. ¼” washers
2 lbs. 6d box nails
4 lbs. 8d box nails
12 pcs. 1” x 6” x 10’ #2 yellow pine

Setting up Forms:

It is important, when bolting the inside forms together, to be sure that the nuts are on the concrete side of the form. This allows the bolts to be backed out (unscrewed), leaving the nuts in the concrete when removing the forms. This precaution is not necessary when endgate rod nuts are used.

It is important to give the concrete side of the forms a coat of used crank case oil just before using. This should be done each time the forms are used. The forms are self-supporting and need no additional bracing.

When forms are in place check them for levelness, squareness, uniformity of wall thickness and position of reinforcing basket before pouring operations are started.

Reinforcing:

The reinforcing should consist of 3/8” reinforcing rods. Cut and bend the rods to proper shape and wire together to form a basket that will fit the center of walls and floor. See Figure 6. Where ends meet they should be lapped 6” and securely wired.

If reinforcing rods are not obtainable, heavy hog wire 32” high may be used as a substitute. It is well to place one ring of reinforcing rod completely around top of tank and about 6” below the top. This rod should be 1/2” diameter or larger. The woven wire should be cut and wired together to form a basket with the same overall dimensions as shown in Figure 6.

Mixing the Concrete:

The best material to use for the concrete is crushed rock and sand or a washed and graded creek gravel and sand. Clean bank run gravel, variable in size and containing a sufficient amount of sand is quite satisfactory. Sometimes by adding sand to bank run gravel a workable mix can be secured. Chat has been used with good success in pouring tanks but varying amounts of sand are necessary. In some cases one part chat to one part sand has been necessary. In other cases when gravel has been almost impossible to get, tanks have been poured using a mixture of sand and cement. Naturally considerably more cement is required when sand is used as the only aggregate.

No definite mix can be given that will fit all conditions. The safest method is to control the amount of water in relation to the amount of cement used. For wet sand use not more than 5 gallons of water per sack of cement; for damp sand use no more than 5 ½ gallons of water per sack of cement, and for dry sand use no more than 6 gallons of water per sack of cement. This process is not difficult to carry out. If only a ½ sack mixer is available, measure one-half of the amounts given for a full sack.

Pour this water in the mixer and add one or two shovels of sand or gravel to keep cement cut loose from mixer then add ½ sack cement. The two quantities of water and cement are fixed and should not be changed. Add gravel and sand in the amounts necessary to make a workable mix. It will facilitate matters to count the shovels of gravel and sand so that when the required number is determined, they need only be counted. The consistency and workability of the mix should be watched and it might be necessary to cut down or add to the sand and gravel from time to time.

Placing Concrete in Forms:

The best method of pouring the concrete is to place it in about 6” layers. Start at one point and continue around the tank. Each layer should be spudded to the extent that all air pockets are worked out and the concrete has been worked out against the face of the forms to secure smooth concrete free from honeycomb. Light tapping of the forms with a hammer slightly below the level of the surface of the layer of concrete being poured helps secure smooth dense concrete. After the forms are ½ to ¾ full the first concrete that has been poured has generally set up to some extent and it is the proper time to level out the concrete that has flowed into the bottom. Add more concrete, and complete the bottom of the tank. Concrete should then be placed in the forms to complete the sides of the tank.

Place six ½”x6” bolts in the top as soon as the concrete is poured. Probably the best location for these bolts is about 1 ½ feet from each corner and one in each end. See Figure 4. These bolts are very useful in insulating the tank or in anchoring material as a protective measure to keep sheep or hogs from being pushed into the tank. About 3 1/2” of the bolts should be in the concrete and leaving about 2 1/2” exposed.

Removal of Forms:

The forms can be removed within two days after pouring the tank in warm weather and within three days during cool weather. However, it is better to leave the forms on a week as they help cure the concrete by keeping it from drying out. It is important to keep concrete damp for a week after pouring.

In removing the forms remove the inside form first. Back out the 8 machine bolts and remove the ends of the inside forms. Less trouble will be experienced if the bolts are not tightened too much when the forms are assembled. The remainder of the forms should come off easily. Any concrete sticking to the forms should be removed as soon as the forms are removed from the tank. A hoe or shovel is a convenient tool for removing this concrete.

Any honeycomb spots should be patched as soon as the forms are removed. To patch these spots work a coat of water and cement mixed to a creamy consistency into the area to be patched with a broom or brush. Then work in a rather stiff mixture of mortar consisting of one part cement and two parts of sand striking it off even with the trowel.

Material Requirement and Other Information:

The tank requires approximately 1½ cubic yards of concrete to pour. In the following bill of material some allowance has been made for waste of sand and gravel.

Aggregate:
1½ cubic yards gravel
1 cubic yard sand
If bank run gravel is used secure 2 cubic yards and some sand if needed.

Cement:
The amount of cement will vary according to the aggregate used. The amount needed will vary from 10 to 15 sacks. Secure 15 sacks and return unused portion.

Reinforcing:
If rod is available: 180’ of 3/8” reinforcing rod
If wire is used: 40 feet 32” wire, 24 feet ½” diameter rod or equivalent

Bolts:
6 – ½” x 6” carriage bolts

Pipe:
This will vary with different conditions. However, the following bill of material is made from Figure 5.

Intake pipe:
1 piece 6’ long. This will be necessary only if the tank is poured before the intake pipe of the tank is connected to the pipe through the dam.
1 elbow
1 piece 3’ long

Drain and Overflow pipe:
1 piece 6’ long – This is horizontal pipe to lead out from under the tank. More will be required in varying quantities to fit different conditions.
1 elbow
1 piece 20” long
1 coupling
1 piece 2’6” long. This is the overflow pipe that screws into coupling in bottom of tank. This length will probably be too long. However, no attempt should be made to cut to correct length until tank is finished as the length will vary slightly for different tanks. Pipe 1 ¼” diameter is preferable. Don’t use less than 1” diameter. Thread all pipe on both ends except 2’6” piece of overflow pipe, which is threaded only on one end.

Insulation:

The inside walls of the tank are sloped to help prevent damage due to freezing. However, the water in the tank should not be allowed to freeze any appreciable amount. If not in use the tank should be drained during the cold months. If it is to be used in winter as many will be it should be insulated against freezing.

One very successful method of insulation is by covering the tank with earth, leaving only 18” of water exposed at one end. (See cover picture.)

Figures 7 and 8 give details of construction with dimensions. Figure 9 shows top and end views of the cover.

Fasten 2×4 headers on top of tank as in Figure 9. Construct tank cover and set in place over the float end of tank.

Set the long posts for the cut-off wall and the short posts at open end of tank. Cover cut-off wall with 2” treated oak planks, spiking them to the long posts. Enclose open end of tank with same material to provide 8” space for insulation. These planks should be bolted to the short posts.

Cover back side of retaining wall with heavy tar paper. (See Figure 10.) Give special attention to sealing joint between retaining wall and tank cover. This joint may be sealed by lapping with tar paper or galvanized iron.

The anchors may be set next and the retaining wall anchored to them with No. 9 galvanized wire. The earth fill may now be made.

Before placing straw insulation around open end of tank the sides and bottom of space to be insulated should be lined with tar paper to help keep insulation dry. Place insulation and construct insulation covers from 1” material and cover with galvanized iron. The front cover should be secured with screen door hooks and made removable so that insulation may be inspected. (See Figure 11.)

An important feature of this insulated tank is the hinged baffle board as shown in Figure 12. The lower edge of this board should extend into but not more than 1” below the water surface in the tank. This baffle prevents cold air from entering float chamber but allows free circulation of water in the tank.

Another feature which may be used to help keep tank from freezing is indicated in Figure 12. Drill one or two 3/8 inch holes near top of overflow pipe and plug. In coldest weather remove one of these plugs and allow a small stream to flow out. This small flow keeps surface of water in the tank slightly agitated and brings in a continuous stream of warmer water from the pond. This flow may be regulated or completely closed off by plugging the holes.

In case the float or valve should need repairing close the valve between the tank and the pond and unscrew the overflow pipe which drains the tank and raise the baffle board. This will provide enough room to get in the tank and reach the float. When the earth fill is completed seed with timothy and red top.

Material requirement for Insulation:
300 f.b.m. 2” x 8” Oak
4 pcs. 2” x 6” x 12’ Oak
5 pcs. 2” x 4” x 8’ Oak
2 pcs. 2” x 4” x 8’ Oak
3 pcs. 1” x 8” x 12’ Oak
4 fence posts 7½ feet long
2 posts 4½ feet long
3 pcs. Galvanized roofing 8’ long
1 pc. Galvanized sheet 18” x 10’
1 lb. roofing nails
1 roll heavy tar paper
15 lbs. #9 galvanized wire
8 lbs. 20d spikes
2 lbs. 8d nails
20 ea. 3/8” x 8” carriage bolts with washers
1 pr. 6” strap hinges
4 screen door hooks
2 gal. wood preservative (carbolineum).

If sheep or small calves are to drink from the tank, additional earth will need to be built up around open end of tank or a ramp constructed from boards.

When this is done the animals should be protected from being pushed into the tank and drowning. One way to do this is to make a suspended platform that will fit into the open end of tank and extend 4 or 5 inches below the water surface. This submerged platform will provide footing for the animal so it can climb out.

The platform may be supported by two ¼” x 1½” pieces of strap iron 5 feet long bent in such a shape that the ends rest on top of the insulation covers, while middle portion extends down inside the tank to the desired level of the platform. Oak boards 1 inch think may be bolted across the bottoms of these supports to complete the platform. Holes should be bored in the boards to provide footing.

Another way to make the platform would be to weld or bolt additional pieces of strap iron across the bottoms of the strap iron supports. The bottom of the basket thus formed would then be covered with hardware cloth or similar material.