Rain water catchment systems are becoming increasingly popular for a multitude of reasons. Most beginning harvesters spend much of their time thinking about which rain barrels they’ll need to buy, how to funnel rain water, and how to store it. These elements may not be the most important, or most challenging, parts though. Distributing the water to where you need it can be an exceptional barrier to using your rain water if you don’t plan ahead.
This is where a water pump for your rain barrel is critical.
While it is an additional cost, its impact on the functionality of your catchment system is dramatic. I cover increasing the water pressure in your rain barrel in another article but the biggest takeaway is that you’re going to have a very hard time getting your water to where you need it without a water pump.
When selecting a water pump though, you’ll have to consider some very important facets to make sure you get the right one.
- The size of the pump
- The type of pump
- The power source
- The cost
The Size Of A Water Pump
When it comes to selecting a water pump, size does matter. It is the crucial factor that determines how much pressure it can generate, and consequently the amount of water that can be pumped. It’s important to get the size just right though. Overdo it, and energy will be wasted due to the inefficiency (which can end up being costly). Don’t get a big enough pump and you won’t get enough water to meet your needs.
Typically, the ‘size’ of a pump is determined by the flow rate. The amount of water that the pump can push in a certain period of time. The equation for flow rate is fairly simple: the volume of water divided by the amount of time. If you’re curious, you can calculate the flow rate for your faucet by taking a measurable container (probably larger than a cup) and measuring how many seconds it takes to fill it.
For a rain barrel pump, this is most often represented as gallons per hour (sometimes gallons per minute) and can range from 300 GPH up to 1,500 GPH or more. Importantly, flow rate and pressure (psi) measure two completely separate things and aren’t interchangeable. What you will need this water for should determine what kind of flow rate you will need. In most cases, you won’t need 1,500 GPH (unless you’re putting out a house fire). If you’re irrigating a garden though, it’s worth knowing what you’ll plant and how much water you’ll need on what timeframe.
Type of Pump
You will also want to consider the type of pump you get and this is where the choices can become a bit overwhelming as there are a bevy of choices (some of which are wrong). For rainwater harvesting, there are three common options:
- Submersible Pump – this is the most common type of pump used. Designed to be submerged, these pumps are really effective at getting water out from the bottom of a barrel which can be difficult with some barrels. Additionally, they are relatively inexpensive and really easy to install, both facets that make this a really popular option. The biggest challenge with submersible pumps is that they can get clogged by sediment, which likes to hang out at the bottom of barrels.
- Centrifugal Pump – This pump sits outside of the barrel and is generally more reliable and effective. You’ll need to find a way to connect this pump to your barrel and perhaps secure it on a base or foundation as well. Compared to submersible pumps though, they can be more expensive and require more maintenance.
- Hand Pump – For those with more modest harvesting systems, such as a single barrel in your garden, a hand pump may make sense. While the flow rate is going to be understandably variable (entirely up to your own endurance), these will be the cheapest and most reliable by far.
Selecting the right pump for your system will ensure the most efficient and effective collection and distribution of your collection. With the right pump, rainwater harvesting can be a sustainable, efficient and cost-effective way to reduce your environmental impact.
Power Source
When you have a water pump you’re going to need to power your pump (Unless you went for the hand pump). Water is heavy and moving it takes a LOT of energy, especially when you need to force it through a hose for a long distance or up an incline. In most cases, gravity isn’t going to do the job for you.
Simply plugging your pump into an outlet is the most common, and most obvious, power source for a rain barrel pump. It’s also likely the most convenient and cost-effective option available to you.
Another option is solar power, which has become increasingly popular for rainwater harvesting systems. If you get plenty of sunlight where your barrels are, solar panels can be reliable, inexpensive, and easy to install. You could be limited by available sunlight though. For example, if you use rain water to water your lawn, it’s typically best practice to water in the morning but the light will be low and may not power your pump.
If you want to see how much sunlight your house or yard gets, this tool from Google will tell you exactly that, though you’ll have to extrapolate a little.
These two are the most common, though power can come from any source that generates electricity. Even wind turbines are an option, though it’s rather unusual for this kind of setup.
Cost
Often the chief concern for most shoppers regardless of the product, cost is an important factor here as well. Before you settle on the cheapest pump, it’s important to know how you want to use your rain water, the amount you’ll need, when you’ll need it, and how you’ll power your pump. Without knowing all of these things ahead of time, you risk needing to buy a replacement pump because the first wasn’t right.
Once you have the previous information though, cost is pretty straightforward. As with any product on the market, the cost of water pumps can vary widely. They range from $40 up to $300. The latter will get you a well pump with a solar panel to charge it though. In most instances, $50-$70 should be enough for a good rain barrel pump.
Let’s Get This Party Pumpin
If you’re going to get a water pump for your catchment system (and you should!) then keeping these four elements in mind will keep you on the right track. Even though the size, type, power source and cost are important elements, the most important thing to know is how you’ll use your rainwater, because it will help inform all of the rest of your decisions.
