Flat-Pack Rainwater Harvesting Modules

Commercial development after rainfall with a prepared subsurface water storage zone

M2015 series · Panel-built PP modules

Two compatible heights for projects that need control over tank depth and freight.

A flat-packed polypropylene module family for underground detention, infiltration and non-potable rainwater reuse. Select the low-profile or higher-volume format, or combine them around the approved project geometry.

Shared 800 × 490 mm footprint 250 mm or 530 mm first tier Recycled or virgin PP

Send project details Compare the two formats

Product family at a glance

Two module heights. One panel footprint.

These panel-built modules are delivered as nested components and assembled close to the excavation. Both formats use the same 800 × 490 mm plan size, while their different heights let a designer refine the underground storage envelope.

800 × 490 mm 31.50 × 19.29 in shared plan footprint

250 / 530 mm 9.84 / 20.87 in first-tier height

92 / 197 L Approx. 24.3 / 52.0 US gal usable storage

94 / 95% Approximate void ratio by format

PP Recycled and virgin polypropylene options

Product scope: HOENSOEY supplies the polypropylene modules and agreed accessories. A completed underground tank also requires project-specific hydraulic design, wrapping materials, pipework, access, pretreatment, earthworks and structural review.

Panel-built construction

A flat-pack format designed around project depth and freight.

Instead of shipping a fully assembled box, the module is formed from molded PP panels that nest for transport and join on site. The low-profile and higher-volume formats share the universal panel a, simplifying mixed-height layouts and project bills of materials.

The model code identifies the panel arrangement; the engineering value lies in the compatible footprint, selectable height and controlled component set.

Nested for delivery

Panels are bundled by type for container loading, site staging and assembly near the work area.

Built from a defined BOM

Each format has a clear panel combination, supporting quantity checks, packing plans and replacement-part control.

Compatible in plan and height

The shared footprint and universal panel allow H and F tiers to be arranged within an engineer-approved layout.

Low-profile arrangement: 2a + 2b + 6c. Connector quantities follow the approved layout.

Exploded view of a higher-volume panel-built rainwater module with a, d and e components — Higher-volume arrangement: 4a + 6d. Connector quantities follow the approved layout.

Format selection

Choose the low-profile or higher-volume format.

Use the lower tier where excavation depth needs closer control or a higher short-term vertical strength option is required. Use the taller tier where more storage per module and fewer vertical interfaces are preferred.

Product reference: M2015H

Low-Profile Format

A 250 mm first tier for shallow layouts, finer height increments and higher stated short-term vertical strength options.

Overall size	800 × 490 × 250 mm 31.50 × 19.29 × 9.84 in
Approx. usable storage	92 L / 24.3 US gal
Approx. void ratio	94%
Panel set	2a + 2b + 6c
Panel-set weight	7.94 kg / 17.5 lb*
Strength options	38 or 50 t/m²*

Higher-volume polypropylene underground rainwater storage module

Product reference: M2015F

Higher-Volume Format

A 530 mm first tier with approximately 197 litres of usable storage and an AASHTO HS-20 tested configuration.

Overall size	800 × 490 × 530 mm 31.50 × 19.29 × 20.87 in
Approx. usable storage	197 L / 52.0 US gal
Approx. void ratio	95%
Panel set	4a + 6d
Panel-set weight	11.82 kg / 26.1 lb*
Strength options	22 or 30 t/m²*

*Panel-set weights exclude connectors and may vary slightly by material grade and production batch. Strength figures are short-term vertical compressive strength options, not allowable project loads.

Adjustable module depth

Shared interface panels make mixed-height layouts possible.

Adjacent vertical tiers share one 20 mm universal panel. For that reason, total height is not the standalone height multiplied by the number of tiers.

Module-only height formula 20 + 230H + 510F mm

H and F are the number of low-profile and higher-volume tiers. Each shared interface panel is counted once.

Standalone and mixed tier examples. Dark separator lines represent the shared universal panel.

1H250 mm / 9.84 in

2H480 mm / 18.90 in

1F530 mm / 20.87 in

2F1,040 mm / 40.94 in

1H + 1F760 mm / 29.92 in

2H + 1F990 mm / 38.98 in

1H + 2F1,270 mm / 50.00 in

2H + 2F1,500 mm / 59.06 in

These figures describe the module stack only. Final excavation and finished levels must also allow for formation, bedding, wrapping, protection, cover, pavement or landscape build-up, pipe interfaces and construction tolerances. Mixed-height use remains subject to an approved structural layout.

Component control

Five flat-packed component types create both formats.

The letter codes provide a simple way to verify the module bill of materials, packing quantities and replacement parts without relying on several similar panel names.

Universal panel, side panel, internal support panels and connector for flat-pack rainwater modules — Component appearance for identification. Final production drawings and the order-specific BOM take precedence.

Code	Component	Nominal dimensions	Unit weight	Standard pack	Primary use
a	Universal standard panel	800 × 490 × 20 mm	1.680 kg / 3.70 lb	8 per bundle	Common to both formats; shared at vertical tier interfaces
b	Low-profile side panel	800 × 210 × 20 mm	0.880 kg / 1.94 lb	10 per bundle	Side closure for the low-profile format
c	Low-profile internal support panel	450 × 210 × 20 mm	0.470 kg / 1.04 lb	10 per bundle	Six internal supports per standalone panel set
d	Higher-volume internal support panel	450 × 490 × 20 mm	0.850 kg / 1.87 lb	10 per bundle	Six internal supports per standalone panel set
e	Connector	Used by connection position	6 g / 0.21 oz	1,240 per box	Horizontal and tier connections; quantity is layout-specific

Low-profile set: 2a + 2b + 6c Higher-volume set: 4a + 6d Connectors: project-specific quantity

Preliminary product selection

Select material and short-term strength by project conditions.

Recycled and virgin polypropylene options are available. The supplied material grade and strength class should be identified in the quotation, technical submittal and applicable test documentation.

Format	Selection class	t/m²	Approx. kPa / psi
Low-profile	Standard	38	373 / 54
Low-profile	Heavy	50	490 / 71
Higher-volume	Standard	22	216 / 31
Higher-volume	Heavy	30	294 / 43

Recycled PP: a value-focused material option for suitable specifications.
Virgin PP: available where the project calls for a defined virgin-resin option or tighter material consistency.
Higher-volume format: an AASHTO HS-20 tested configuration is available; request the applicable test scope and limitations.

Representative M2015H short-term compression test load displacement curve — Representative M2015H compression test curve. Match the report to the exact version being supplied.

Polypropylene rainwater module in a vertical load test setup — Product load-test setup. Test conditions and acceptance criteria belong in the project review.

Engineering boundary: short-term vertical compressive strength is not an allowable installed load. Cover, pavement, soil and backfill, groundwater, traffic, layer count, lateral pressure, construction loading, safety factors and long-term material behaviour must be reviewed for the actual project.

Three hydraulic purposes

Detention, infiltration or non-potable rainwater reuse.

The module creates underground void space. The surrounding liner, pretreatment, pipework, outlet control, access and maintenance plan determine how the completed tank operates.

Detention

Temporarily holds runoff and releases it through a designed outlet or flow-control device. The tank is normally lined, with protective geotextile selected for the project build-up.

Infiltration

Uses a permeable geotextile wrap so stored water can enter suitable surrounding soil. Infiltration testing, seasonal groundwater, nearby structures and contamination risk must be checked first.

Non-Potable Reuse

Stores captured rainwater inside a watertight lining for an approved reuse such as irrigation. Pretreatment, water quality, pumps, controls, overflow and local requirements remain part of the complete design.

The same module can sit inside different water-management arrangements, but those arrangements are not interchangeable. For broader context, see the U.S. EPA overview of green infrastructure types.

Typical project settings

Underground storage without giving up the surface use.

A modular layout can be arranged beneath trafficked or landscaped areas when the full structure, cover, access and local approvals are designed for that use.

Parking lot as a typical surface use above underground rainwater storage

Parking & Road Areas

Subject to pavement, cover and traffic-load verification.

Civic plaza as a typical setting for underground rainwater storage

Civic & Commercial Plazas

Coordinates storage with public-space levels and services.

Sports field as a typical application for subsurface rainwater storage

Sports Fields

Preserves the playing surface while using space below grade.

Park landscape as a typical application for underground rainwater collection and reuse

Parks & Landscapes

Supports detention, infiltration or irrigation-water reuse.

Images illustrate typical application settings and should not be presented as named M2015 case studies unless corresponding project records are available.

From factory bundle to excavation

Nested components for bulk freight and site assembly.

Panels are bundled by component type, allowing a high quantity of installed gross module volume to move in a container. Final packing depends on order mix, protection, container limits and the confirmed loading plan.

Workers installing underground rainwater storage modules in a lined excavation beside a building construction site — **Project-scale underground storage installation** Modular storage units positioned within a lined excavation before final wrapping, inspection and backfill.

Bundled flat-pack polypropylene rainwater module panels prepared for container loading — Nested panel bundles staged for shipment. Actual bundle and pallet protection follow the order plan.

Underground rainwater storage modules assembled and wrapped within an excavation — Modules aligned in the excavation before the wrapping and backfill sequence is completed.

01
Sort
Stage the required a, b, c, d and e components near the assembly area.
02
Assemble
Form each panel module and confirm that its joints are fully seated.
03
Connect
Build the approved grid in rows and tiers, including shared interface panels.
04
Wrap & interface
Complete the specified geotextile or geomembrane build-up, pipe penetrations and access details.
05
Backfill
Protect and backfill the tank in the approved sequence using the specified material and equipment.

Format	Container	Approx. module quantity	Approx. installed gross volume
Low-profile	20-ft GP	860	84.3 m³ / 2,977 ft³
Low-profile	40-ft GP	1,800	176.4 m³ / 6,229 ft³
Low-profile	40-ft HC	2,050	201.0 m³ / 7,098 ft³
Higher-volume	20-ft GP	520	108.0 m³ / 3,814 ft³
Higher-volume	40-ft GP	1,050	218.0 m³ / 7,699 ft³
Higher-volume	40-ft HC	1,200	249.0 m³ / 8,793 ft³

All container figures are approximate. Final quantity may vary with container dimensions and limits, order mix, bundle protection, loading practice and the confirmed packing list. Installation must follow approved project documents; the sequence above is not a project method statement.

Commercial supply

China manufacturing support for projects, wholesale and OEM programs.

The flat-pack format is aimed at project quantities and repeat supply. HOENSOEY can prepare a product-and-logistics proposal around the required volume, site constraints, target strength class and delivery destination.

Project Supply

For contractors, drainage specialists, developers and engineering-led procurement.

Preliminary H/F quantity and tier combination
Order-specific component BOM
Packing and container estimate
Available technical documents for review

Wholesale & Distribution

For importers and regional partners purchasing for stock or multiple projects.

Mixed-format order planning
Bundle and labeling coordination
Repeat-order component control
Market-specific sales material support

OEM Cooperation

Private-label and product-development items can be discussed against a defined business case.

Material, color and packaging requirements
Branding and documentation scope
Controlled product modifications
MOQ, tooling and validation review

OEM changes are not assumed to be interchangeable with tested standard versions. Any change affecting material, geometry or structural performance requires a separate technical and commercial review.

A better first quotation

Send the inputs that determine a workable configuration.

Required cubic metres alone are not enough to select the format or confirm quantity. A useful enquiry also explains the available geometry, hydraulic purpose, loading and site conditions.

Project country, location and delivery address

Required usable storage volume

Available length, width and module depth

Detention, infiltration or reuse purpose

Finished surface use and traffic class

Cover and pavement or landscape build-up

Soil, groundwater and infiltration information

Inlet, outlet, pipe levels and access requirements

Required material or documentation

Target order date, Incoterm and destination

Request a preliminary configuration

Read: 9 checks before specifying underground storage → View the broader underground storage module range → See the M2025 column-type option →

Practical questions

Frequently asked questions.

What is a flat-pack rainwater harvesting module?

It is a polypropylene underground storage module supplied as nested molded panels rather than a fully assembled box. The panels are assembled on site and connected into the approved tank layout.

What is the difference between the two module formats?

The low-profile format is 250 mm high and stores approximately 92 L per standalone module. The higher-volume format is 530 mm high and stores approximately 197 L. Both have the same 800 × 490 mm plan footprint.

Can low-profile and higher-volume tiers be combined?

Yes. They share the universal panel and can be combined in an engineer-approved layout. The module-only height is 20 + 230H + 510F mm, where H and F are the number of each tier.

Why is the height not the standalone module height multiplied by the number of tiers?

Adjacent vertical tiers share one 20 mm universal panel. A second low-profile tier therefore adds 230 mm, while a second higher-volume tier adds 510 mm.

Is the module a complete underground tank system?

No. The product creates the structural void space. A completed tank also requires project-specific hydraulic design, geotextile or geomembrane, pipework, access, pretreatment, earthworks, backfill and structural approval.

Which polypropylene material options are available?

Recycled PP and virgin PP options are available. The quotation and technical submittal should identify the supplied material and the test evidence applicable to that version.

Does short-term compressive strength equal the allowable installed load?

No. Project design must also consider cover, pavement, soil and backfill, groundwater, traffic, lateral pressure, construction loading, layer count, long-term behaviour and the required safety factors.

Can the same modules be used for detention, infiltration and reuse?

Potentially, yes, but the surrounding arrangement changes. Infiltration normally uses a permeable geotextile, while detention or reuse generally needs a watertight liner plus project-specific controls, pretreatment and access.

Are bulk supply, distributor orders and OEM cooperation available?

Yes. HOENSOEY supplies project and repeat-order quantities from China. Private-label packaging, color, material and controlled product changes can be discussed subject to MOQ, tooling and validation requirements.

What information is needed for a preliminary configuration and quotation?

Send the required usable storage, available length and width, depth limit, hydraulic purpose, cover, finished surface use, traffic class, soil and groundwater information, pipe levels, project location and delivery destination.

Project enquiry

Request a preliminary configuration and quotation.

Send the available project information, even if the layout is not final. We can begin with a practical review of format, quantity, material, packing and the documents available for discussion.

Useful attachments and data

Drainage or civil drawing
Required usable storage volume
Available tank footprint and depth
Surface loading and cover build-up
Inlet and outlet levels
Project location and delivery destination

Prefer email? Write to roger@hoensoey.com.

Product information on this page supports preliminary selection and commercial discussion. Final design and installation remain subject to qualified engineering review and applicable local requirements.