Stormwater Capture Doesn't Have to Be Complicated: A Contractor's Case for Simpler Rain Harvesting Systems

Low Impact Development rules in the City of Los Angeles apply to new construction and large expansions, and they push projects to keep rain on site and to harvest and reuse it. Many other Southern California cities and the County have similar requirements. That is a good goal. The trouble is how often the systems drawn to meet it end up far more complicated, expensive and fragile than the job needs.

We build these systems in the ground. Here is what we see, and how a civil contractor can help the design team get the same performance with less complexity.

Where packaged systems get complicated

Plan sets often call for packaged systems from the large national manufacturers, such as Contech Engineered Solutions and its CDS separators, StormFilter cartridges and DuroMaxx cisterns. These are well-engineered, widely accepted products. The issue isn't quality. It is how much system gets specified, and what that does to cost, schedule and maintenance.

• Proprietary everything. Separators, vaults, pump skids and controls that come from one source, with parts nobody else stocks.
• Long lead times. Fabricated units that have to be ordered weeks or months ahead, which locks the schedule to a factory.
• Crane-set components. Heavy precast or packaged units that need a crane, rigging and room for both, which tight lots and hillside streets often don't have.
• Control-panel-heavy pumping. Multiple pumps, sensors and a digital panel that only a factory-trained technician can troubleshoot.
• Maintenance nobody planned for. Owners inherit a system that needs a specialist service contract to keep running, and when a part fails, irrigation stops until it arrives.

None of this means those products don't work. They do. But on many projects they are more machine than the requirement calls for, and the owner pays for that complexity at every stage: ordering, delivery, rigging, installation and every year of maintenance after.

What a capture-and-use system actually has to do

Strip it down and every system does the same few things:

1. Keep trash and sediment out before water is stored.
2. Store the water until it is used or released.
3. Pump it to where it is reused, usually irrigation.
4. Back it up with city water when the cistern runs low, without ever mixing the two.
5. Overflow safely to an approved discharge when it is full.

Each of those can usually be done with standard materials and methods that the City and County already review all the time.

A simpler way to build each part

Pretreatment

Instead of a crane-set separator unit, a standard precast tank fitted with a commercially available filter insert can keep debris out of storage. It sets with ordinary equipment, and it cleans out like any other tank.

Storage

Storage can be a lined chamber bed with rock, or a basin built from standard large-diameter pipe on a concrete pad with a traffic-rated lid. These are materials supply houses carry, delivered on a regular truck.

Pumping

Modern variable-speed pressure pumps are compact, quiet and smart. A single unit can act as both the transfer pump and the pressure booster, holding steady pressure to the irrigation system as demand changes, with no separate control panel. Where suction lift is a concern, a submersible version sits at the bottom of the basin so the pump never runs dry. Parts and replacements are standard, so a failure is a short service call, not a long wait.

City water backup, done the safe way

The part that gets health departments' attention is cross-connection, any chance of harvested water getting into the drinking water. The cleanest answer we have built is simple:

• Irrigation connects only to the pump, so everything irrigated comes from the harvested side.
• A float sends city water into the pump basin through an air gap when the level is low. There is no valve switching city and harvested water on the irrigation line.
• The float is set at the outfall elevation from the cistern into the pump basin, so city water only tops up the pump basin and never fills the cistern.

The air gap keeps the potable supply protected, and a direct mainline feed through it keeps up with any irrigation zone during dry months. A modest reserve in the pump basin is enough without digging deeper.

Overflow

Overflow goes to the discharge the civil engineer's plan already calls for. Simple, visible and easy to inspect.

Redundancy and efficiency, together

Simpler doesn't mean less protected. This approach builds in redundancy where it counts: irrigation keeps running on city backup when the cistern is dry, the air gap protects the water supply, and standard parts mean a failure doesn't shut the system down for weeks. At the same time it creates efficiencies everywhere else:

• Ordering: standard materials from local supply houses, short lead times.
• Delivery and rigging: regular trucks and equipment, often no crane.
• Installation: fewer fabricated pieces and fewer connections to get wrong.
• Maintenance: any trained technician can service it, with parts on the shelf.

The savings aren't about one product being cheaper than another. They come from building the whole system around parts that are easy to buy, install and keep running.

How it works on your project

A contractor doesn't design the system. The civil engineer or Engineer of Record does, and submits it to the agency. Our part is to:

• Review the plan set early and flag where the specified system is heavier than the requirement.
• Propose alternates with standard materials, pumping and make-up details for the engineer to accept or decline.
• Price the specified system and the alternate side by side so the owner can see the difference.
• Build whichever the engineer approves, and help the owner understand how to maintain it.

Approvals are project by project. On past projects, alternates like these have been reviewed and accepted through the civil engineer and the agency. That is the right path every time, and it is why bringing us in early matters. Read more about bringing the underground contractor in early, and see how fitting the system to the site and building tanks in place can save up to six figures.

Where this fits best

• Commercial and multi-family projects with LID capture-and-use requirements.
• Tight or hillside sites where a crane is hard to get in.
• Owners who want a system their own maintenance team can understand.

How we help

JFPEC builds stormwater capture, pretreatment, storage, pumping and drainage systems across Greater Los Angeles, with our own crews. Send us your plan set at any stage and we will show you where it can be simpler. Call (800) 606-3880 or request a bid.