There are 4 diameters of drip tape on the market. The smallest and most common size is ⅝”. The other sizes are ⅞”, 1 ⅛” & 1 ⅜”. The majority of drip tape sold is ⅝”. If you are purchasing drip tape for a garden or small farm where row lengths are 600 feet or less then we highly recommend the ⅝” tape. The larger sizes are only used in large farming operations.
Wall thickness of drip irrigation tape is measured in mil. Available thicknesses range from 5 - 15 mil. With 5mil being the thinnest and 15 mil being the thickest. If you are new to using drip tape we strongly recommend starting with 15 mil. The thinner walled tape is less forgiving and can be damaged easily by someone that is unfamiliar with drip tape installation.
For home garden use we always recommend 15 mil tape. As it will last several seasons whereas the thinner walled tape will only provide one maybe two seasons of use. 15 mil tape is more expensive, however, being able to use it for multiple seasons will make it less expensive in the long run. Below is a chart of available wall thicknesses and expected longevity.
|Wall Thickness||Life Expectancy|
|5 mil||1 year|
|6 mil||1 year|
|8 mil||2-3 years|
|10 mil||2-4 years|
|12 mil||2-4 years|
|15 mil||5-10 years|
Drip tape has pre-set drip points built into the tape. So there is no need to buy additional drippers/emitters. It is important to note that no additional emitters can be added to drip tape. Unlike poly tubing, no holes can be punched into dip tape to allow for the insertion of barbed drippers. Emitters are spaced at one set distance for the entire roll of tape. For home gardens the most popular spacing is 12”. That means every 12” there will be a drip point for the entire run of tape. Emitter spacing is normally matched to the type of crop being watered. Below is a chart with popular emitter spacings and what crops or application use that emitter spacing.
|Emitter Spacing (in inches)||Crops or Application||Other Considerations|
|4"||Flowers, Peppers, Greenhouses||Good for Sandy Soil, Short Runs|
|6"||Germination, Onions, Garlic||Tight Plant Spacings|
|8"||Germination, Strawberries, Vegetables||High Flow for Sandy Soil|
|12"||Good all around choice||If Low Flow Emitter Used - Great for Long Runs|
|60"||Blueberries, Hops||Long Runs of Plants Spaced Far Apart|
When selecting the flow rate for your drip tape there are 3 considerations to keep in mind.
Run Length –The longer the run length you need per row of tape then the lower the flow rate per emitter is needed. The reason is that longer run lengths have more emitters and the more emitters there are the more water is being used per line. Thus, in order not to exceed the capacity of a system lower emitter flow rates are used to accommodate for longer runs of tape. For anyone that needs run lengths of 500 feet plus, we recommend using a “low flow” emitter (see chart below).
When planning a home garden tape system run length is not going to be a limiting factor because the rows are generally short and any of the emitter flow rates can be used.
Soil Type –No matter the scale of your drip tape system soil type is a consideration that everyone should think about. The three main types of soil are Clay, Loam and Sand. Below is the flow rate selection for each soil type.
|Soil Type||Soil Characteristics||Emitter Suggestion|
|Clay||Does not drain well||Low Flow: .11-.16 Gallons Per Hour (GPH)|
|Loam||Drains well||Medium or High Flow: .18 -.46 GPH|
|Sand||Drains the fastest||High Flow: .33-.46 GPH|
Filtration – It is important to keep in mind that when choosing emitter flow rate that the lower the flow an emitter has, the smaller the opening for water to drip out is. This means that lower flow emitters can be more susceptible to clogging. So it is very important that if using a low flow emitter to have a good filter with at least 200 mesh. If you know you have water that is hard or has mineral build up it would be best to go with a high flow emitter to prolong the life of the drip tape.
Why does drip tape need to operate at a low pressure? – Drip tape is thinner walled than drip irrigation tubing and is designed to work at low pressure. Too much pressure can cause the tape to burst. It is important that a pressure regulator is installed in your tape system to ensure that the system is operating at or below the specified maximum operating pressure listed. Below is a guide on maximum operating pressure for different sizes of drip tape.
|Wall Thickness (mil)||5/8" Tape||7/8" Tape||1 1/8" Tape||1 3/8" Tape|
|6||10 PSI||8 PSI|
|8||15 PSI||10 PSI||8 PSI|
|10||15 PSI||15 PSI||10 PSI|
|12||15 PSI||15 PSI||12 PSI|
|15||15 PSI||15 PSI||15 PSI||15 PSI|