Search

Link copied!
Application page header image

Rainstore3 FAQ

A Better Way to Contain the Rain

See Rainstore3 questions and answers below. if you have a question that is not covered, please reach out.

< All FAQ Sections

Rainstore3

What is Rainstore3?

Rainstore3 is a modular stackable underground water/liquid containment system. It is installed subsurface to be used as detention basins and retention harvesting systems. Made from 100% recycled plastic, units come preassembled for easy drop-in-installation.

What are the advantages of Rainstore3?

There are many advantages to the Rainstore3 system. The Rainstore3 system comes shipped to the job site pre-assembled for easy drop in installation. It's taken off the pallets dropped onto the geogrid, geotextile and wrapped up. Other advantages are that it is scalable so it's perfect for small residential projects where you've got a small cubic foot of water storage that you need to meet all the way up to a massive unlimited water storage amount. Some of the advantages compared to other systems out there are that the Rainstore3 requires no gravel fill. So, depending on where the project is sourced it can be really expensive to have to ship in and this is not the case with the Invisible Structures Rainstore3

Is Rainstore3 just for commercial applications or is it residential as well?

Rainstore3 is great for residential or commercial projects. Rainstore3 is often needed for residential projects to meet run off requirements on new developments and the advantage to Rainstore3 is it is scalable, so it's perfect under downspouts. Rainstore3 is also great for commercial applications because of its size and scalability to create large basins.

Can Rainstore3 be used in a harvesting system?

Rainstore3 can be used in a harvesting system, where that system is encapsulated by a impermeable liner holding the water in that tank, which can then be pumped and reused for gray water reuse, irrigation, etc.

What are the common applications for Rainstore3?

Rainstore3 is a solution for stormwater retention and detention as well as other applications requiring liquid storage. Water will percolate through the ground or covering and can either run through Rainstrore3 at a controlled rate or be stored for later use. Common applications include:

  • Underground Detention Basin
  • Retention/Harvesting Systems
  • Water/Rain Gardens
  • Green Roofs
  • Sports Field Drainage
  • Downspout Catch Basins
  • Utility Liquid Battery Storage

What are the main advantages of Rainstore3?

Rainstore3, arrives pre-assembled, for easy installation. It is modular and stackable so can be installed in a wide range of depths, maximizing the capacity of water storage.

What is the cost of Rainstore3?

Please see our Rainstore3 Estimator for product cost.

What is stormwater management?

Stormwater management is anything designed to mitigate the adverse effects of stormwater such as flooding, mud, rutting, pooling and general lack of drainage. All Invisible Structures products are designed to address these issues.

What is an underground detention system?

Underground detention systems include any structure or vessel designed to store rainwater or other liquid beneath the surface of the ground. A primary function of the vessel is stormwater management. Rainwater can be captured and fed back into the Earth to replenish groundwater or collected and harvested for future use. Storing water underground provides additional security as well. Examples of underground detention systems include arched chambers and plastic modular systems such as Rainstore3.

What are rainwater collection systems?

"Rainwater Collection Systems include any vessel, tank or other basin that is designed to collect and store excess rainwater. Examples of these are barrels, concrete storage tanks, arched chambers, detention basins and plastic modular systems – such as Rainstore3. Reasons to collect excess stormwater vary from flood prevention to harvesting for the purpose of reuse. The efficacy of these systems differ based on size and design.

Rain barrels and concrete storage tanks are limited in their capacity because of their impervious walls, whereas arched chambers, detention basins, and plastic modular systems have unlimited capacity. Arched chambers and plastic modular systems have the advantage of storing water underground, allowing for usable space such as parking lots or green spaces on top.


Only Rainstore3 is strong enough to support the weight of structures such as a parking garage or small building."

Should I use a rainwater collection system?

"There are several reasons to use a rainwater collection system. In areas with heavy rainfall where drainage is an issue, these systems can help mitigate the problems caused by flooding. All climates, including arid, can benefit by capturing rainfall and harvesting the water for reuse. Reusing water can save money and provide environmental benefits.

Another advantage of underground rainwater collection systems, not designed for harvesting, is that they can replenish the groundwater. Water shortages and the decrease in our ground water are among the planet’s biggest environmental concerns today."

What types of rainwater collection systems are there?

There are several different types of Rainwater Collection systems. These include rain barrels, concrete storage tanks, arch chambers, milkcrate systems, and other plastic modular systems – such as Rainstore3. These different systems vary in size, cost, ease of installation and water storage/void capacity.

Rain barrels are the least expensive and do not require professional installation. Their capacity is limited by the size of the barrel. Concrete storage tanks are moderate in cost, also limited by their tank size, and require professional installation.


Arch chambers require a sizable installation area and a considerable amount of gravel fill which can be expensive. The void space is 40 – 50%. Milkcrate systems are mid-range in price but require complex assembly, which can add to the cost of labor. Their capacity is unlimited.


Modular plastic storage systems tend to be the highest initial cost but installation is relatively simple. Their capacity is also unlimited. Another benefit to plastic modular systems is the high void capacity and strength – Rainstore3 exceeds H-20 loading.

What is the weight capacity of Rainstore3?

Rainstore3 exceeds H-20 loading allowing it to support vehicular traffic, lightweight buildings or greenspace. Please see our H-20/Hs-20 Guide for more information.

What are the sizes of the Rainstore3 system?

Rainstore3 individual modules were done in metric so they measure one meter wide by one meter long by 1/10th of a meter high. That's about 40 inches by 40 inches by four inches. These can be stacked on top of each other depending on your sight all the way from four inches, all the way up to eight feet high.

How much water can Rainstore3 hold?

Rainstore3 is 94% void space. A single unit holds almost 25 gallons, which means each cubic meter is capable of holding up to 250 gallons.

How are rainwater collection systems used?

Rainwater Collection Systems are used for either water detention or water harvesting. Either method is an effective way to control stormwater for flood prevention. For reuse, water harvesting is required from an impervious vessel or storage basin. Harvested water can be used as gray water, for agricultural purposes or can be purified and used as potable water.


Water detention basins allow water to seep back into the ground recharging the ground water. The depletion of ground water has become one of the biggest environmental concerns our planet is facing.


All collection systems require some minimal maintenance in order to maintain optimal functionality.

How much rainwater can a rainwater collection system collect?

The amount of rainwater which can be collected varies by the type and size of the collection system used. Rain barrels typically hold 50 – 55 gallons per barrel. A rainfall of ½” on a 1,000 sq. ft. roof will fill one barrel. Concrete and plastic storage tanks range in size from 250 gallons to 15,000 gallons.

Arch chambers, milkcrate and plastic modular systems are only limited by the length, width and depth of the area as well as the void space of the system. For example, arch chambers provide only 40 – 50% space for water whereas Rainstore3 provides 96%. Therefore, each 1 meter piece of Rainstore3 holds up to 25 gallons, even though it’s only 4” high. At the maximum depth of almost 8’, 24 units of stacked Rainstore3 can hold almost 600 gallons of water in a single stack.

What is the installation process for Rainstore3?

Rainstore3 can be installed in two different ways. One where you have an infiltration system where the Rainstore3 is just wrapped up in a geotextile fabric, that allows water to infiltrate into the system in a big storm water surge and exfiltrate back into the ground. You can also incorporate an impermeable liner around either just the sides and the bottom of the system or around the entire system to create a harvesting system. Rainstore3 comes in preassembled custom height stacks that can be unloaded and dropped directly into the job site. Installation is fast and easy. For additional details please see the Rainstore3 Installation Guide.

How close to the foundation can Rainstore3 be installed?

We recommend a minimum of 36 inches between the foundation and the edge of the Rainstore3 system. If space does not allow for that, you can do an installation at a max of 12 inches as long as you use an impermeable liner to prevent the water from reaching the foundation.

How are the inlet/outlet pipes attached to Rainstore3?

Inlet and outlet pipes can be attached to Rainstore3 by forming a “boot” with the fabric or liner and securing it with a hose clamp.

How much cover is required over the Rainstore3 system?

A minimum of 12” of compacted road base and a geogrid layer is required above the Rainstore3 chambers.

What keeps the soil from entering the cells?

Rainstore3 is wrapped in a geotextile fabric or PVC liner so soil and vegetation are unable to penetrate the chamber.

Can Rainstore3 be inspected after it is installed?

Adding maintenance ports during installation allows Rainstore3 to be inspected after the installation is complete. Please see the Rainstore3 Maintenance Guide for Details.

Is silt buildup an issue?

Silt buildup can be prevented by using proper pre-filtration, such as catch basins or sediment filters. Using Rainstore3 in conjunction with Grasspave2 or Gravelpave2 can eliminate the need for any filtration systems as the water would be filtered naturally through bioremediation.