5. Outlets to let water out of the pond

96 You will need an outlet to let water out of your pond when you want to empty it.

97 You should place the outlet at the bottom of the bank at the lower end of your pond at the deepest part.

Simple outlets

98 The outlet can be made from a piece of heavy bamboo or a pipe of plastic or metal. The outlet pipe should be about 10 centimetres in diameter. The bank of your pond is much wider at the lower end than at the upper end, so the outlet pipe will have to be longer than the inlet pipe.

99 The outlet pipe should be long enough to reach through the bottom of the bank from one side to the other. You will need a pipe about 6.5 metres long to reach through the bank at the lower end of your pond.

Figure 64

Figure 65

100 If you cannot get a pipe that is long enough to go through the bank, you can join shorter pieces of pipe together using straight pieces of pipe like the ones in the drawing.

101 If you are using bamboo, you can join short pieces of bamboo together with pieces of smaller bamboo in the centre, but the smaller pieces should be at least 8 to 9 centimetres in diameter. Wrap the bamboo joints with rope and close them with tar to keep water from seeping out.

Figure 66

Figure 67

102 Now dig a gap in the bank where you want the outlet to be. It should reach from the deepest part on the inside of the pond through the bank to the outside of the pond.

103 If the outlet pipe is below ground level on the outside of the pond, you will have to dig a ditch to take the water away from the outlet.

104 Put the outlet pipe in the gap in the bank and rebuild the bank over it.

105 If you use an outlet of about 10 centimetres in diameter, it will take about 10 hours to empty your 400 square metre pond.

106 It is easier to place the outlet where you want it to be before you dig out the centre of the pond and build the banks. When you build another pond, you will understand this and you will be able to do it when you are building the banks. But now, when you are building your first pond, you should place the outlet in the way you have just learned because it is easier to understand.

Figure 68

A better outlet

107 If you use a plastic or metal pipe for the outlet of your pond, you can make it better by putting an upright length of pipe on the end of the outlet using an L or a T piece like the ones in the drawing. Close the T piece with a plug as shown.

108 Put the L or T piece and the upright pipe on the end of the outlet outside the pond, but protect it so that it cannot be reached by animals or other people.

109 The top of the upright pipe should reach about 3 to 5 centimetres above the water level of your pond. If the water rises above this level, it will overflow from the upright pipe.

Figure 69

Figure 70

110 Tie the upright pipe to a pole that has been pounded into the ground so that it will not slip down and let the water out of the pond before you want it to.

111 When you want to let out the water, untie the upright pipe and push it down. The water will then flow out of the pond.

112 There is still another way to let water out of your pond, using a siphon. You will learn how to use a siphon in items 122 to 133.

Figure 71

Figure 72

Another kind of outlet: The monk

113 You can build another kind of outlet to empty a bigger pond faster. It is built inside the bank at the deep end of the pond. This kind of outlet is called a monk. When the pond is filled, the monk will be in the water.

114 A monk is a tall box with two sides, a back, a front formed by wooden boards and a bottom. Each side has two slots to hold two rows of wooden boards.

115 Boards are put into the slots to keep water in the pond or taken out to let water out.

Figure 73

116 A monk has a screen that fits on top of the first row of boards. It keeps your fish from getting out when the pond is too full or when you are emptying it.

117 A monk also serves as an overflow, so you will not need to have an overflow pipe like the one shown in item 109.

118 You can build a monk from wood, or if you know how to build with bricks or blocks, you can use these.

119 The drawings on the next pages will show you how to build a monk using wood, and how to fill and empty a pond using a monk.

Figure 74

Figure 75 - BUILDING A WOODEN MONK

Figure 76 - WHERE TO PUT A MONK IN THE POND

Figure 77 - PARTS OF A WOODEN MONK

120 You can further improve a pipe outlet by placing a collar of cement around the centre of the pipe. The collar will hold the pipe in place in the bank and keep water from seeping through the bank outside the pipe.

121 The following drawings show you how to build a wooden form to make a cement collar.

Figure 78

Figure 79

Using a siphon to drain your pond

122 You will also be able to use a siphon to empty your pond. If you use a siphon, you will not need an outlet but you will need an overflow like the one described in items 172 to 179.

123 A siphon is a simple tube that runs from the inside of the pond over the bank and lies on the ground outside the pond.

124 A siphon can be made of plastic or rubber tubing at least 3 centimetres in diameter.

Figure 80

125 The siphon must be long enough to reach from the deepest part of the pond and run over the top of the bank and down the outside of the bank. You will need a siphon about 8 metres long to reach over the top of the bank from the deep part to the outside.

126 When you are ready to empty your pond, put ail of the siphon into the pond. It will fill with water. Be sure the tube is full of water from one end to the other. If the siphon is not full of water, it will not work.

Figure 81

Figure 82

127 While the siphon is still in the water, close one end of the tube with a plug and leave the other end open.

128 Leave the open end of the siphon below the surface of the water. You can use stones to hold the siphon under the water, but be sure that they are not so heavy that the water will be shut off.

129 Take the other end of the siphon, which is closed with the plug. Lift it over the top of the bank and put it on the ground outside the pond.

130 If the ground on the outside of the pond is higher than the pond bottom at the deepest part, you will have to dig a ditch so that the end of the siphon on the outside of the pond will be lower than the end of the siphon in the pond. The ditch will also take the water away when you empty your pond.

Figure 83

Figure 84

131 Now, take the plug out of the siphon. If the end on the outside is lower than the end in the pond and if the end in the pond is under water, water will start to flow through the tube and out of your pond.

132 If the end of the siphon in the pond comes to the surface, the water may stop flowing. If this happens, put the whole siphon into the pond to fill it with water and begin again.

133 It will take a lot more time to empty a pond with a siphon than with an outlet. If you use a siphon of about 3 centimetres in diameter, it will take about three days to empty your pond.

Figure 85

Summary
YOU HAVE LEARNED HOW TO DRAIN WATER OUT OF EACH POND

Provide an outlet for each pond:

• locate it through the bottom of the lower-end bank
• make its bottom about 10 cm below the deepest point in the pond
• use a straight pipe, an L-pipe or a monk

Or use a siphon made from a flexible tube at least 3 cm in diameter