Photo Source -> University Of Arizona College Of Agriculture And Life Sciences
Rainwater harvesting isn’t just a hobby—it’s a smart investment in water conservation, self-sufficiency, and sustainability. But before you jump in, you’ve got a big decision to make.
Wet system or dry system?
This choice comes down to how your plumbing is set up.
A dry system is simple—water flows directly from your roof into a storage tank, and the pipes empty completely after each rain.
A wet system, on the other hand, uses underground plumbing that stays filled with water between rains, allowing for more flexible tank placement but requiring extra maintenance.
I’ve spent nearly two decades helping people capture and store rainwater efficiently, and I can tell you this—choosing the right system upfront will save you a ton of money, frustration, and maintenance headaches down the road.
Some homeowners assume all rainwater collection systems work the same way. Not true.
A dry system is straightforward, with pipes that drain completely after each rain. A wet system, on the other hand, uses underground piping that stays filled with water until the next rainfall. Each has its place, but choosing the wrong one can leave you dealing with mosquito infestations, clogged pipes, or even frozen plumbing in the winter.
So, which one is right for you? That depends on a few factors:
How much water do you want to collect?
How much space do you have for your tank?
Do you care about aesthetics or hiding pipes underground?
Are you willing to handle extra maintenance and costs?
What Are Wet and Dry Rainwater Harvesting Systems?
When setting up a rainwater collection system, your plumbing configuration plays a major role in efficiency, maintenance, and cost. The two primary options—wet and dry systems—determine how water moves from your roof to your storage tank.
Let’s break them down.
Dry Rainwater Harvesting System: The Simple, No-Fuss Approach
Photo Source -> University Of California Davis, (Graftman, 2017)
A dry rainwater harvesting system is as straightforward as it gets. The pipes run directly from your gutters to your storage tank, with no underground piping involved. After a rainstorm, the pipes drain completely, eliminating any standing water.
Best for: Homeowners with a small roof catchment area, DIY enthusiasts, and those looking for a low-maintenance, budget-friendly solution.
Key Benefits
Lower cost—no expensive underground piping or excavation required.
Easy to install—perfect for DIY setups.
No standing water—prevents mosquito breeding and water stagnation.
Minimal maintenance—no need to flush pipes or worry about clogs.
Things to Consider
The tank must be placed close to the roofline.
Exposed pipes may not be aesthetically pleasing.
Limited ability to collect water from multiple downspouts.
Is a Pump Necessary for a Dry System?
Not usually! Dry systems rely on gravity to move water from the roof to the tank. However, if your tank is positioned far from where you need the water—say, for irrigation—you may want to add a small pump for extra pressure.
Helpful Resource -> best roof for rainwater harvesting
Which System Works Best for a Small Yard?
A dry system is the way to go. Since it doesn’t require underground piping, it’s much easier to fit into a tight space without digging trenches or rerouting plumbing.
If your property has limited space and you want an easy, reliable rainwater collection setup, a dry system is often the best choice. But if you need to place your tank farther away or connect multiple downspouts, you may need to consider a wet system—which we’ll cover next.
Wet Rainwater Harvesting System: The Hidden, High-Capacity Solution
Photo Source -> Penn State Extension
A wet rainwater harvesting system is designed for properties that need to collect water from multiple downspouts or where tank placement flexibility is a priority. Unlike dry systems, a wet system uses underground pipes to transport rainwater to a storage tank. Because the pipes are lower than the tank inlet, water remains in them between rain events—hence the name "wet system."
Large properties, urban homes where aesthetics matter, and setups requiring multiple roof catchment areas.
Key Benefits
Tank placement flexibility—can be positioned away from the house.
More aesthetically pleasing—no exposed pipes along walls or ground.
Great for multiple downspouts—allows consolidation from different roof areas.
Efficient for large-scale collection—ideal for high-volume water storage.
Things to Consider
Higher installation costs—requires underground piping and excavation.
Potential for standing water—pipes retain water, which can lead to stagnation.
More maintenance needed—regular flushing and inspections required.
Risk of pipe freezing in colder climates if water isn’t drained properly.
I Have Multiple Roof Areas. What’s My Best Option?
A wet system is more efficient for collecting water from several downspouts. Instead of running separate above-ground pipes to a single tank (which can get messy and impractical), underground pipes consolidate everything into one storage unit.
This is a major advantage for homeowners with complex rooflines or multiple buildings on their property.
How Do I Prevent Mosquitoes in a Wet System?
Since wet systems retain water in the pipes, standing water can become a breeding ground for mosquitoes. The best way to prevent this is to:
Use first flush diverters—flush out stagnant water before fresh rainwater enters the tank.
Install pipe screens—block mosquitoes from accessing water inside the system.
Drain pipes between rains—ensure no water sits in the pipes longer than necessary.
While wet systems offer greater flexibility and a cleaner aesthetic, they require more planning, maintenance, and upfront costs than dry systems. If you don’t need the benefits of a wet system, a dry setup might be the smarter choice.
Pros and Cons of Wet vs. Dry Rainwater Harvesting Systems
Both systems have their place, but if you want a low-maintenance, cost-effective setup, a dry system is often the better choice. If you need more flexibility in tank placement and a hidden pipe design, a wet system might be worth the extra cost and maintenance.
Key Cost Differences: Which One Is More Expensive?
When it comes to cost, the biggest difference between wet and dry rainwater harvesting systems comes down to installation and maintenance. While both systems serve the same purpose, wet systems require more materials, labor, and upkeep, making them the more expensive option.
Helpful Resource -> Rainwater Harvesting System Cost | Full Breakdown
Installation Costs
Dry systems are cheaper and easier to install since they use above-ground piping that drains automatically. There’s no need for excavation, underground piping, or specialized drainage systems, making them a popular choice for DIYers and budget-conscious homeowners.
Wet systems require underground trenches, additional piping, and sometimes pumps, which significantly increase installation costs. If your system spans multiple downspouts or requires complex routing, professional installation may be necessary, further driving up the price.
Maintenance Costs
Dry systems require very little maintenance. Since the pipes drain after each rainfall, there’s no risk of stagnant water, reducing the likelihood of clogs, mosquito breeding, or pipe damage.
Wet systems need ongoing maintenance to keep pipes clean and functional. You may need:
Mosquito-proofing (pipe screens and first flush diverters).
Periodic flushing to remove stagnant water and debris.
Repairs if underground pipes develop leaks or blockages.
DIY vs. Professional Installation
Dry systems are DIY-friendly, making them the better option for homeowners who want a simple, cost-effective setup. With basic tools and materials, most people can install a dry system without professional help.
Wet systems, due to their underground infrastructure, often require a professional installer, which adds to the upfront cost. If not properly designed, wet systems can develop drainage issues, leaks, or freezing problems in cold climates, making professional expertise even more essential.
Which is Better for Cold Climates?
If you live in a region where temperatures drop below freezing, choosing the right rainwater harvesting system is critical. Frozen pipes, ice blockages, and expansion-related damage can all wreak havoc on an improperly designed system.
Helpful Resource -> How To Winterize Rain Barrel
Dry Systems: The Better Choice for Cold Climates
No underground pipes = no freezing risk. Since dry systems rely on above-ground pipes that empty completely after each rainfall, there’s no risk of water sitting inside pipes and freezing.
Less maintenance in winter. Once your tank is full, there’s no need to worry about flushing pipes or draining retained water.
Easier to winterize. Many homeowners simply disconnect or drain the system during the coldest months to prevent damage.
Wet Systems: Extra Precautions Needed
Underground pipes can freeze. Water sitting in the pipes between rain events can turn to ice, leading to blockages or even burst pipes.
Drainage solutions are necessary. Some wet system owners install automatic drain valves to remove standing water from pipes before freezing temperatures hit. Others use heat tape or insulation to protect underground sections.
Risk of damage. If freezing occurs and isn’t properly managed, pipes can crack or rupture, leading to costly repairs.
If you live in a cold climate, a dry system is the safer, lower-maintenance option. It naturally drains itself after each rainfall, preventing any risk of freezing.
If you must use a wet system—due to tank placement or multiple downspouts—be prepared to invest in drainage solutions, insulation, or heated pipes to prevent winter damage. Otherwise, expect to do seasonal maintenance to keep your system functional year-round.
Final Verdict: Which System Is Best for You?
When it comes down to it, the best rainwater harvesting system depends on your property layout, budget, and long-term maintenance preferences. However, for the majority of rainwater harvesting enthusiasts, your choice will be a dry system.
Choose a Dry System If
You want a low-cost, easy-to-maintain setup.
Your tank can be placed close to the roofline.
You prefer a DIY-friendly installation with minimal ongoing maintenance.
You live in a cold climate, where underground pipes could freeze.
Choose a Wet System If
You want a cleaner aesthetic with no visible pipes.
You need to collect rainwater from multiple downspouts or buildings.
You’re okay with higher installation and maintenance costs for added flexibility.
You have limited space near the house and need to place your tank farther away.
Ready to Start Harvesting Rainwater?
Visit AquaBarrel today to find the best rainwater harvesting solutions for your home!