Gravity Feed Guidelines

These guidelines are included to help you achieve the most consistent water output from each of the drip emitters. It might not be practical for you to follow each of these guidelines with your particular landscape or garden layout. The more of these guidelines that you incorporate into the design of your gravity feed drip system, the more consistent drip emitter output you will achieve.

1. Emitter output drops off down the line as you move farther away from the supply line. The graph below shows the emitter output for a single line of 1/2 gph drippers (DD-TAE10) attached to a rain barrel (Starter Kit). In this example, the rain barrel is installed 2 ft above the ground and filled with 2 ft of water. Ten drip emitters were spaced every 24 inches along the 1/2” drip tubing (20 feet total). As you can see below, the individual emitter output decreases toward the end of the drip tubing.

Single 20 foot length of drip tubing - Mainline attached at end.

2. Use short drip tubing runs & a grid layout. You will get better results with grid layouts of short tubing lengths (20 ft or less) than with a long snaking drip tube.

Blue circles are rain barrels

The chart below shows how the installation of short rows will reduce emitter output variance. This example results for three 20-foot rows. The rain barrel is installed 2 ft above the ground and filled with 2 ft of water. Each 20-foot line of drip tubing has ten drip emitters spaced every 24 inches from beginning to end (30 total emitters). Water supply is connected next to Line #1. If the total distance was covered by a single “snaking’ line of drip tubing, you would see a large drop in water output between the first and last emitter on the line (like the graph above).

Three rows of drip tubing - Mainline attached near end of line #1

3. Connect mainline to the center of the row to create a more even distribution. By splitting the distance between lines # 1 and #3 you can even out the water output along the drip line.

Rain Barrel & 3 rows of drip tubing

In the chart below, notice how the output is increased throughout the system and the output is relatively even between all of the emitters. The rain barrel is installed 2 ft above the ground and filled with 2 ft of water. Each 20-foot line of drip tubing has ten drip emitters spaced every 24 inches from beginning to end (30 total emitters). Water supply is connected at the end/center of the grid next to Line #2.

Three rows of drip tubing - Mainline attached in center near end of line #2

Another option is to attach the mainline to the center of the grid, like this:

Mainline attached in center

4. When installing multiple rows, connect the ends together to further reduce the variance in emitter water distribution. Our research shows that by connecting the ends of the drip tubing you can improve the pressure in the line and lessen the drop in flow rate.

Mainline in center - closed drip tubing ends

In the chart below, there is even less variance in drip emitter output (vs. the previous example). The rain barrel is installed 2 ft above the ground and filled with 2 ft of water. Each 20-foot line of drip tubing has ten drip emitters spaced every 24 inches from beginning to end (30 total emitters). Water supply is connected in the center of the grid next to Line #2.

Three rows of drip tubing - Mainline attached in center near line #2 - closed drip tubing ends

Ref 6020