Harvesting Aqua

How to increase water pressure from rain barrels

If you’re new to collecting rain water, an issue you may not have considered at the outset is the water pressure of your system. It’s not something you’ve had to think about when you can just flip on any faucet in your home connected to a municipal water supply but pressurized water is a luxury we often taken for granted. A lot goes into delivering water to your home at 40-50 psi that you simply don’t see.

It’s not enough to just collect rain water, you need to get it to where you want to use it too and low pressure can make this a challenge. This is true especially if you need the water to travel a significant distance like for an irrigation setup (which you should do since rainwater is better for plants).

Here, I go over how to increase the water pressure from rain barrels and the steps you can take to use the water you’ve harvested for the purposes you intended.

Get a pump

I’m going to go ahead and save you a bunch of time right off the bat. Just get a pump.

If you were hoping that there would be a quick and easy way to increase the pressure of the water flow from your rain barrel, well, there really isn’t. Nothing else that you can do is going to be as effective as an electric pump. Every other factor that I’ll go through here will help increase pressure but won’t give you the oh-so-satisfying flow you’ve come to expect from your faucet or hose. Ultimately, there is no better solution to water pressure than to install a water pump and enjoy the consistent pressure that it delivers.

This isn’t to say that pumps don’t come with their own challenges. First off, pumps aren’t free, and many can go for $50 – $100 each. Fortunately, you can find them pretty easily at a local garden center. Additionally, you’ll have to overcome some logistical challenges including installing the pump and providing power, so your placement options may be limited. Finally, you can’t just get any pump. The sizing of the pump is an important step that this guide can help you with.  Still, these challenges are minor compared to the ease and efficiency of the solution.

More volume equals more pressure

If you want more pressure without a pump, then a bigger barrel will be critical. As many of us learned in high school science, higher water levels increase pressure at the bottom (the deepest parts of the ocean have so much pressure it could crush a person). Because of this, the more water there is, the more pressure you’re going to have.

This is especially important to keep in mind in a few instances when building your collection system. When chaining multiple barrels together, you’ll want the one you’re drawing water out of to stay as full as possible. Additionally, when placing a spigot, the lower on the barrel you can place the spigot, the more pressure you will get. The water at the bottom of a barrel has more pressure than the water at the top. If pressure is something you’re really going to need, then get a bigger barrel.

There is a trick that can help though as the total number of gallons of water isn’t exactly all that drives pressure but it’s how the water stacks, or more accurately, how tall your water barrel is. Carefully choosing the facets of your rain barrel can make a huge difference. If all of your water is stored in a short and wide tank like a kiddie pool, there will be no downward pressure to create the flow you will need to push your rainwater out of a garden hose. Getting a taller rain barrel can help improve the pressure.

Build a rain barrel stand

Height doesn’t necessarily need to be delivered by the height of the barrel either, gravity can play an important role here as well. You can deliver the height necessary to create pressure by placing your rain barrel on an elevated platform. Any additional height you can add will add to the pressure built up in your hose.

Be forewarned though, this can only get you so much additional pressure. You will need a lot of height in order to drive sufficient pressure from a platform alone. Remember that lovely pressure we took for granted in our kitchen faucet? The reason your home gets so much pressure is that the city built a water tower, typically on one of the highest locations in the area and it’s tall. In order to get similar pressure, you will need to build your own towers up to approximately 30 feet of elevation. Unless you’re willing to build a water tower in your backyard, you’re going to have to settle with a bit less.

height comparison of water tower to increase pressure

This doesn’t even account for how you’re going to get your rainwater up to the reservoir of a water tower, which might require a pump (see why I said ‘just get a pump’?). Unless you’re willing to build a water tower in your backyard, you’re going to have to settle with a bit less.

It’s important when choosing between a platform and a pump to understand the costs. While pumps might seem more expensive at their face value, a platform may be more expensive depending on how you choose to build it. The cost of lumber could quickly and easily add up to the same as a pump, if not more (especially if you do want a water tower).

Your garden hose matters less than you think

It would be natural to think that a smaller hose would result in more pressure. After all, if you put your thumb over the end of the hose, you get more distance. To a certain degree, this is true but it doesn’t mean that a smaller diameter garden hose will lead to more pressure. Without any pressure, water will make its way to the end of your hose anyway, the pressure is entirely dependent on the source of water: your rain barrels. A smaller diameter hose may get you a nominal increase in pressure but not enough that it’s going to solve all of your problems.

This doesn’t mean that your hose size doesn’t matter though. When choosing a hose, even though the pressure matters less, the flow rate is important. Flow rate is different than water pressure as pressure describes the power at which water exits the hose but flow rate describes how much water is capable of being delivered and this is heavily impacted by the diameter of the hose. Think of it this way, with a flow rate that is half of a larger hose, you will need twice as long to water your garden. So before you run out to get a smaller hose to increase you pressure, consider how it will impact the flow rate too.

For those of you planning to use your hose for gardening, a soaker hose may be a great alternative. These don’t require as much pressure since they leak water as it goes through. Generally, a soaker hose needs about 8 to 10 pounds per square inch to function. If this is your goal, you may not need a water pump or full-blown water tower in your backyard, an elevated platform can get you the pressure that you need.

Can it go the distance?

Finally, one more important factor is how far you need your water to travel. The pressure you build up from gravity alone represents the amount of pressure you have at the spigot of your barrel. The farther away from the barrel you need the water to travel, the less pressure there will be at the end. Especially if a portion of the path that water needs to travel goes above the water’s surface or even your spigot. Going against gravity can reduce your pressure dramatically.

This is particularly important for anyone using their collected rainwater for irrigation purposes as you may need your water to travel quite a distance. When building a rain water harvesting system, it’s crucial to consider where you want to use the water you’ve collected, how far it will need to travel, and over what terrain.

Read The Guide To Rainwater Harvesting

Check out our comprehensive guide to rainwater harvesting and its many benefits

Rainwater Calculator

*0.62 Gallons

100,000 Gallons Per Year