Rainwater Harvesting Cistern Install: A Real-World, Ohio Health Department Approved Example
Planning a rainwater harvesting cistern install? This guide walks you through a complete, real-world installation we completed for a residential customer — built to Ohio Health Department standards, which are among the most stringent in the United States. If your system can pass Ohio's requirements, it can pass virtually anywhere.
This installation centers on a 5,500-gallon precast concrete underground cistern paired with a full above-ground filtration and treatment train. All components used in this install are available through our catalog, or you can request a quote for a complete system install and we'll spec it out for you.
Watch the full rainwater harvesting cistern install from excavation to final filtration — a real Ohio Health Department approved system built by Rain Brothers.
Why Ohio Health Department Standards?
Ohio's regulations for potable rainwater harvesting systems require multi-stage filtration, NSF-certified components, proper overflow management, and documented installation practices. By designing to these standards, you get a system that is safe, durable, and defensible — whether you're on a rural property, a homestead, or a commercial site. Every component in this install was selected to meet or exceed those requirements.
Step-by-Step Rainwater Harvesting Cistern Install
Step 1: Excavate the Cistern Pit and Bed
Excavate the cistern pit to the required depth and dimensions for your tank. Prepare a level bed of 4–6" of crushed stone or sand. Proper bedding is critical — an unlevel or soft base can cause the tank to shift over time, stressing inlet and outlet connections. Take your time here; it's the foundation of the entire rainwater harvesting cistern install.
Step 2: Dig the Water Supply Trench
Trench from the cistern to the house for the water supply line. The trench must run below the local frost line to prevent freezing — in Ohio, that's typically 36–42" deep. Slope the trench slightly toward the cistern so any condensation or minor leaks drain away from the structure.
Step 3: Drill Through the Foundation Wall
Core drill a hole through the foundation wall sized for both the waterline and electrical conduit. Plan this penetration carefully — you'll need to seal it with hydraulic cement inside and out at the end of the install, so a clean, tight hole makes that job much easier.
Step 4: Set the Cistern Tank
Lower the precast concrete cistern into the prepared pit using a crane or excavator. Verify it is level in all directions before backfilling. Concrete cisterns are the preferred choice for potable rainwater systems — they are structurally robust, chemically inert, and naturally buffer pH.
Step 5: Connect the Water Line and Electrical Cabling
Run the water supply line and electrical conduit from the cistern to the house through the trench. The pump in this system is submersible and lives inside the cistern, so the electrical cable runs from the pump up through the access riser and into conduit. Use waterproof wire connectors and protect all penetrations with conduit fittings rated for direct burial.
Step 6: Install Downspout Drainage Trenching
Trench from each downspout collection point to the roofwasher location. Install 4" solid-core Schedule 40 PVC and bed the pipe with crushed stone, sand, or clean fill. Ensure consistent fall (minimum 1/8" per foot) toward the roofwasher so collected rainwater flows freely and doesn't pond in the pipe.
Step 7: Install the Roofwasher Pre-Filter
The roofwasher is the first line of defense in any rainwater harvesting cistern install — it removes leaves, debris, and the first-flush contaminants before water ever enters the tank. For this project we used the Wisy Vortex Roofwasher, which uses centrifugal action to self-clean and requires minimal maintenance. Size your roofwasher to match your roof's square footage — we carry models rated from residential up to large commercial applications.
Step 8: Install the Overflow
Every cistern needs a properly sized overflow to handle storm events that exceed tank capacity. Route the overflow from the roofwasher and from the cistern itself to a suitable discharge point — a dry well, infiltration trench, or daylight outlet. Ohio Health Department standards require the overflow to be protected against backflow and pest entry.
Step 9: Install Rodent and Mosquito Guards
All open pipe ends — overflow outlets, vents, and discharge points — must be fitted with pest exclusion screens. This prevents mosquitoes from breeding in standing water and rodents from entering the system. We use a high-flow Mozzie Stoppa overflow guard with removable screen for easy cleaning.
Step 10: Bed the Roofwasher and Seal All Joints
Backfill around the roofwasher housing with crushed stone to provide drainage and stability. Wrap and caulk all pipe joints at the roofwasher using the manufacturer-specified sealant (Wisy recommends their own joint compound). A watertight installation here prevents soil infiltration and keeps your pre-filter performing as designed.
Step 11: Complete Remaining Drainage Runs
Tie in any remaining downspouts or surface drains to the collection system. Double-check fall on every pipe run — water must always flow toward the cistern, never away from it. This is a common source of problems in DIY rainwater harvesting cistern installs that gets overlooked until the first heavy rain.
Step 12: Backfill and Grade
Backfill the cistern pit and all trenches in lifts, compacting as you go to prevent settling. Grade the surface to direct surface runoff away from the cistern access riser. Pro tip: If other contractors (septic, utility) may need to excavate nearby in the future, consider leaving a marker or leaving pipe ends slightly exposed so they can locate your system without damage.
Step 13: Install Interior Controls and Filtration
This is where the rainwater harvesting cistern install comes together inside the home. Run the waterline and electrical conduit through the foundation wall penetration and connect to the pressure tank. The submersible pump inside the cistern pressurizes the system. From there, install the following treatment train in sequence:
- Shut-off valve immediately downstream of the pressure tank
- Two-stage sediment filtration (down to 5-micron absolute) — use only NSF-approved filter housings for potable applications
- NSF Class A UV Sterilizer — provides continuous biological disinfection without chemicals
- Smooth-nosed sample tap immediately after the UV unit for water quality testing
- Main water shut-off valve at the end of the treatment train
Seal the foundation wall penetration with hydraulic cement on both the interior and exterior faces. This is a code requirement under Ohio Health Department standards and prevents groundwater intrusion.
Optional: Tank Level Monitoring
We strongly recommend adding a WiFi-enabled tank level gauge so you can monitor cistern volume from your phone. This is especially valuable during dry spells when you want to track consumption and plan accordingly.
Get the Complete Ohio Health Department Approved System
Don't want to source components individually? We offer a pre-configured Ohio Health Department Approved Complete System that includes everything you need for a code-compliant rainwater harvesting cistern install. All components are available through our catalog, or request a quote and our team will build a custom spec for your property.
