Why Use Poly (Polyethylene) Tubing (Instead of your garden hose)?
A common question we frequently receive is “Can I connect my system to my garden hose?” and it is a great question. Understandably, a garden hose seems very easy to use, as it is usually already connected to the hose bibb and conveniently reaches out to the garden. However, a garden hose may not be the best solution for your system. This is because garden hoses are made from many different materials and may have different inside and outside diameters than poly tubing.
Why does this matter?
This matters because any channel that water passes through causes friction loss and the size of the tube or hose that the water travels through has a maximum flow rate capacity (GPH) and pressure (PSI) it can withstand. If the GPH or PSI capacity is exceeded, this can ultimately cause a noticeable loss of pressure and/or flow in the system. Meaning, you may have a flow rate of 200 GPH at your hose bibb and a pressure of 35 PSI, but once the water travels through the garden hose, it may drop down to 150 GPH and 25 PSI.
Garden hoses vary in size and wall thickness. Unfortunately, there are no standards in garden hoses, and due to this, we are unable to accurately say what friction loss or capacities for flow rate and pressure (PSI) yours can be used with.
Whereas poly tubing has specific pressure and flow rate specifications. This helps to avoid unexpected decreases in pressure or flow due to friction loss. While poly tubing nominal sizes can vary between different manufacturers, each size has inside/outside diameters noted and standard specifications for maximum flow and pressure.
At Drip Depot, we standardized our poly tubing using inside and outside diameters. All of our tubing have these diameters listed on the item page. For example, our ½” poly tubing has an inside diameter of .600” and an outside diameter of .700”. This size is able to supply up to 200 GPH maximum and can run for 200 feet with minimal flow or pressure loss. To learn more about tubing sizes and what size works best for you, here is our Tubing Buying Guide.
Using poly tubing instead of a garden hose allows you to get the most out of your system and maximize your existing resources - such as the flow rate from the hose bibb. Using poly tubing also allows you to accurately gauge your system - by knowing the maximum capacities of the system components, you can ensure that the system is operating as optimally as possible, and the performance of all of the watering devices are as expected.
If you do plan to use a garden hose, and there is simply no way around it, there are a few things you can do.
The most important thing to remember is to do that flow rate (GPH) and pressure (PSI) test at the end of the garden hose. This will give you a more precise specification and expectation for your system.
Garden hoses also cannot be under constant pressure, so a timer will need to be installed before the hose (if you are using a timer).
Garden hoses should be considered/factored into the total run length of the mainline, if you plan to install the head assembly at the spigot before the garden hose.
You may find it more beneficial to install the rest of the head assembly (Backflow Preventer, Filter, Pressure Regulator, 1/2" Swivel adapter or tubing adapter) between the garden hose and the poly tubing/system. However, either way will work.
Here is an example of a head assembly with ½” tubing without a garden hose:
Here is an example of a head assembly with a garden hose incorporated in the system:
If you can help it, we recommend using polyethylene (poly) tubing instead of a garden hose. You’ll likely have an easier time setting things up and calculating the system specifications using a poly tubing, rather than with a garden hose.
It is important to remember that any and all channels water passes through will cause friction loss. Knowing the inside diameter of tubing or a hose can be helpful in calculating or estimating the possible friction loss and how this will impact the GPH and PSI of the system.
If you do plan to use a garden hose, we always recommend testing the GPH and PSI of your system at the end of your garden hose.
Your garden hose is not able to be installed under constant pressure. To relieve the constant pressure, we recommend placing your timer (if you are using one) on the spigot, before the garden hose.
If you plan to install the head assembly components before the garden hose, you will want to count this towards your total run length (to help account for PSI/ GPH loss).
Lastly, for best results with a garden hose, we recommend installing the timer first, then the garden hose, followed by the backflow Preventer, filter, pressure regulator, 1/2" Swivel adapter or tubing adapter.
If you have any questions after reading this article, please reach out to our knowledgeable agents at our helpdesk.