You’ve heard me say that water is only as clean as the container you store it in, so it only makes sense that I do a post about the best ways to store rainwater, right? 

The point of appropriately storing rainwater is all about health and sanitation: rainwater just sitting in a container easily grows algae, becomes a breeding ground for mosquitoes or other nasty critters, and gets a bad smell. That’s why properly storing your rainwater is important.

The best way to store a large amount of rainwater for the least amount of money is in the ground.  By constructing swales, ponds and basins in which rainwater is directed into, you can store a large amount of water in the soil which is pumped back up to the surface in the form of fruit trees and a thriving garden.

Now, if you are harvesting rainwater for domestic purposes as well, then you might need to store rainwater in some sort of container. Don’t worry, I’ve covered those options too, read on to learn about the best ways to store rainwater you intend for in-home, personal use, as well.

Slow It, Sink It, Spread It: Using Earthworks To Harvest Water

Earthworks are basically a landscaping design that channels rainwater where you want it to go.  The idea is to slow the water down, spread it out as much as possible and allow it to sink into the soil. 

Not only does this help to rehydrate the soil naturally, but over time, it can even increase the groundwater of your location.  On one project where I installed earthworks in an otherwise arid climate, I found natural springs popup that bubbled water for months after a rainfall.

Earthworks can include swales built on contour to the slope of the land, basins dug to catch rainfall that is directed into them, broadscale plowing with a method known as keylining, creating checkdams to slow water down and so on.

If your property is small, you may be able to create many of these earthworks by hand, meaning the cost to begin storing your own rainwater comes down to you and a shovel.

But even if you employ the cost of an excavator or crew of workers to create your earthworks for you, dollar for dollar, the amount of water you can save in the soil will greatly outpace what you can store in a tank.

Once you’ve completed the landscaping changes, there should be almost no maintenance. Simply plant some edible plants near the constructed earthwork so that itʻs roots can tap into the harvested water and enjoy the fruits of your labor.

The most obvious limitation of Earthworks is that the harvested rainwater is only directed to your property, leaving you without harvested water for domestic purposes. 

Obviously, we humans need water to live, too.  This approach doesn’t provide water for cooking, cleaning, laundry or bathing, so you will still need storage tanks for your at-home water needs.   

For domestic water, you should consider one of these other options for storing rainwater in a container on your homestead.  Just remember to send all the overflow into your earthworks.

Container Storage of Rainwater

The two best types of tanks for storing rainwater are ferro cement and stainless steel. These are both strong, durable solutions that will last for years, but, admittedly, they are very expensive. Cheaper solutions include polyurethane tanks or the common ‘blue barrels’.

Ferrocement Tanks

Ferrocement has an estimated lifespan of 100 years, so these guys are gonna last your lifetime, easy. They are also incredibly durable: being weatherproof, hurricane-proof, and can even withstand earthquakes.

They aren’t cheap, though, but with their strength and how long they last, you can see why.

Yes, you can save money and DIY your own ferrocement tank, but materials are not cheap for this type of tank, which will still make it more expensive than other types of water tanks.

Stainless Steel Tanks

Contrary to what you might immediately think about ‘steel’, these guys won’t corrode or rust. It’s stainless steel coated with chromium oxide that allows it to stand up to nature, temperature change, moisture, and even chemical treatments you add to the water, without corroding. 

Stainless steel tanks are well-designed, usually with liners if you’re using the water for domestic purposes.

Unfortunately, you aren’t going to easily build your own stainless steel tank (unless you’re a trained welder, then hey, go for it!), and they are not cheap. However, they last a long time (30 years and counting), so consider the initial cost to purchase one of these tanks as an investment.

Polyurethane Tanks

Polyurethane tanks are a popular option for storing water because: 1) they are affordable, 2) don’t require you to dig up your property to get started storing rainwater, and 3) they last a long time.

Polyurethane water tanks can last up to 20 years and are specially made to hold up to the strong UV rays of the sun. This makes them a good choice for homesteaders, especially someone who’s just starting out with harvesting rainwater.

There are both above-ground and underground poly tanks, depending on your needs that come in a range of sizes from a 100 gallons to 10,000 gallons.

Slimline Tanks or Barrels

Now, slimline tanks or barrels are similar to Polyurethane tanks, the only difference might be in size, shape, and sometimes, material.

The estimated lifespan is just like polytanks – 20 years, as long as the tanks are either out of direct sunlight or made with UV-resistant material. A good way to keep slimline tanks out of the sun is to construct a building or shelter for them.

For the homesteader that is storing water above ground, slimline tanks are a good water storage option that takes up minimal space. However, you’re also going to have less water stored, which may or may not be a problem, depending on how regularly you get rain and how quickly you use your stored water.

Barrels, on the other hand, are probably your cheapest method. You can easily access your water (to treat it and use it), but the drawback is that you have a lot less storage capacity and underground storage isn’t practical.

The good news is, since barrels are cheap and easy to get, you can start storing your rainwater right away, without needing to construct anything or prepare your property for underground tanks.

How Big Should My Rainwater Tank Be?

Determining the size of water tank (or, the overall capacity of your rain barrels) for your homestead boils down to several factors: how much rain your area regularly receives and how much water your family uses.

For every 1” of rain on a 1000 sq ft roof, you can collect 600 gallons of water.  They say the average family uses 300 gallons of water per day although my family of 4 has been able to get that down to 50 gallons per day.  Thatʻs roughly 18,000 gallons per year if youʻre being frugal, 110k if youʻre average, or Iʻd like to say, wasteful.

In Hawaii where we get 150” of rain per year, all we need is a 3000 gallon water tank and weʻre doing pretty well.  But in the drier parts of the island where the rainfall averages 20” per year, you may need at least a 10k gallon tank and a larger roof catchment surface to catch all the water youʻll need.

Run your own numbers and see how much rainfall you can catch on your own site.  I bet the numbers will surprise you.

State Laws for Rainwater Collection

Before we go, another factor to consider are the legal requirements in your location. 

Many people don’t think of this, but states do have laws around rainwater collection.  Some states frown upon it while others actively encourage it and even offer incentives for setting up a good rainwater catchment system.

States with Incentives

There are some states that give you tax advantages for having a rainwater collection system, so make sure to take advantage!

  • New Mexico
  • New Jersey
  • Arizona
  • Maryland
  • Florida
  • Michigan
  • Hawaii
  • Pennsylvania
  • Oklahoma
  • Wyoming

States with Regulations

Regulations around rainwater collection usually means that you need a permit, may only use the water for ‘non-potable purposes’, or there is a limit of the size of tank you can use. 

Unfortunately, this may limit what type of rainwater storage option you choose, simply because you’re limited to how much you are legally allowed to store.

  • Arkansas
  • Colorado
  • Georgia
  • North Dakota
  • Illinois
  • Nevada
  • Utah

And, some states, like California, Texas, Oregon and North Carolina, have both regulations and incentives around rainwater harvesting, so make sure your tanks are permitted before you start.