From detention to reuse (non-potable applications)

When detention storage is coupled with appropriate treatment, that water can become a reliable non-potable supply for:

• Cooling-tower make-up
• Irrigation
• Toilet/urinal flushing
• Process water, washdown, decorative water features, etc.

A typical reuse train for stormwater includes:

1. Screening/pretreatment (trash, grit, gross solids)
2. Filtration/UF (suspended solids, turbidity)
3. Disinfection (UV and/or chlorine)
4. Polishing/storage with controls, monitoring, and make-safe bypasses

Many detention assets (vaults, chambers, ponds) can double as the primary capture reservoir, with a pumped draw-off to a treatment skid that feeds end uses. Several vault products explicitly support harvesting configurations.

Detention vs. Retention: Key Differences

Although the terms are often used interchangeably, detention and retention describe very different stormwater management strategies. Detention systems temporarily store runoff and then release it slowly to downstream sewers or waterways, primarily to control peak flows and reduce flooding risk. By contrast, retention systems (sometimes called infiltration or retention basins) are designed to hold water permanently on site—either allowing it to infiltrate into the ground, evaporate, or be harvested for reuse. In practice, detention is usually a regulatory requirement for flood control, while retention provides additional water-quality and sustainability benefits by keeping water out of municipal systems altogether.

How Wahaso supports design—and leverages detention assets

Wahaso works upstream with owners, architects, and MEP/civil teams to:

• Identify viable sources (stormwater, rainwater, condensate, greywater) and end uses.
• Integrate with detention: We can draw from existing or planned detention (including detention ponds) as the capture source, minimizing new footprint.
• Engineer the treatment train to local code/permit requirements and desired water-quality targets (cooling towers, irrigation, toilets).
• Provide controls/monitoring for reliability, compliance data, and O&M simplicity.

Reference projects using detention/capture for reuse

• Orange Memorial Park Regional Stormwater Capture Project (South San Francisco, CA): Regional project that diverts flows from Colma Creek, pretreats, stores in an underground cistern, and applies advanced treatment for non-potable reuse—illustrating the detention-to-reuse pathway at scale.
  
• Bolivar (Simón Bolívar) Park, Lakewood, CA: Stormwater is diverted from a flood-control channel, pre-treated, and conveyed into a StormTrap system; Wahaso’s published case study notes the system manages tens of millions of gallons annually, producing water suitable for spray irrigation and offsetting >4 million gallons/year of municipal supply.

Selecting the right detention platform for reuse

• Footprint & cover: Precast vaults excel under traffic with shallow cover; arches/crates shine where excavation depth is limited.
• Volume & geometry: CMP/SRPE pipes scale easily for long, linear footprints; modular precast optimizes cubic storage under parking fields.
• Maintenance access: Precast vaults typically offer the best internal access; arches/crates demand upstream pretreatment and clear maintenance plans.
• Regulatory objectives: If detention is the permit driver, weirs/orifices govern outflow; for reuse, add the treatment skid, QA monitoring, and potable make-up safeguards (code-driven). Products like StormTrap/StormCapture explicitly support detention and harvesting configurations.

Bottom line

Detention infrastructure isn’t just a compliance cost center. With the right platform and a Wahaso treatment/control package, it becomes a distributed water supply for cooling towers, irrigation, toilet flushing, and more—often yielding operational savings, LEED contributions, and resilience benefits while still meeting stormwater peak-flow requirements.