Rainwater Collection System Inspection Checklist
A rain system does not fail overnight. It drifts. This inspection walk checks every component against last season and catches the drift while it is still a ten-minute fix.
Kit coverage
0%
0 of 28 items handled · tick states are saved on this device only.
Catchment and roof inspection
The water is only ever as clean as the first surface it lands on.
- CORERoof surface checked for rust, broken tiles, overhanging branches and any bird or leaf load Amazon
- CORERoofing material confirmed safe for collection; no asbestos cement, lead flashings or weathered coating Amazon
- Gutters checked for correct fall toward the downpipe and for standing water Amazon
- Downpipe joints and brackets inspected for cracks, splits and a secure fit to the wall Amazon
First-flush and inlet inspection
Confirm the diverter is actually diverting, not quietly bypassing.
- COREFirst-flush diverter confirmed present, its held volume re-checked against the true roof area Amazon
- COREDiverter drain tested: open it and confirm the held volume empties fully and freely Amazon
- Calmed inlet inspected inside the tank to confirm it still directs flow to the floor Amazon
- Leaf screen and tank-inlet mesh checked for tears, sagging and gaps larger than one millimetre Amazon
Tank structure and seal inspection
The tank holds thousands of kilograms. Inspect the body and every opening.
- CORETank exterior walked all the way round for cracks, bulges, weeping seams or UV damage Amazon
- Manhole lid and gasket inspected for a tight seal with no hardening or cracks Amazon
- COREAll openings confirmed mosquito-proof, with no gap a rodent or frog could enter Amazon
- Foundation and ground beneath the tank checked for settlement, erosion or a leaning base Amazon
Overflow and drainage inspection
A full tank needs an honest escape route for the next storm.
- COREOverflow pipe checked for correct size and an unobstructed outlet screen Amazon
- Overflow discharge path confirmed to carry water clear of building footings and the tank base Amazon
- Surge capacity noted before the wet season so a storm is not lost from a full tank Amazon
- Any diversion or pump-out fitted to the overflow tested to confirm it still routes as intended Amazon
Pump and pressure inspection
Test the pump under load. A pump that runs is not always a pump that works.
- COREPump start and stop observed under load for normal pressure, noise and cycling Amazon
- Pressure-tank pre-charge checked; a waterlogged bladder is a hard-to-spot fault Amazon
- Non-return valve and prime confirmed; a pump that loses prime signals a suction leak Amazon
- COREElectrical supply, earthing and RCD protection at the pump tested for safety Amazon
Distribution pipework and leak inspection
The losses that matter are the ones you cannot see at the tank.
- Every accessible joint and fitting inspected for weeping, corrosion and a secure connection Amazon
- COREGround walked along buried runs for unexplained wet patches, sinkholes or lush growth Amazon
- Exposed pipe insulated or shielded against freeze damage for the coming cold season Amazon
- COREBackflow prevention or a break tank confirmed where rainwater meets any mains connection Amazon
Water quality and documentation inspection
An inspection that is not written down is only a memory.
- COREA sample drawn and taste-and-smell checked at the kitchen tap, not only the tank outlet Amazon
- Test-strip readings for pH, turbidity, nitrate and bacteria recorded with the date Amazon
- COREA dated photograph of every component saved so the next inspection can compare Amazon
- A written action list made: pass, monitor or fix, ordered by safety and quality impact Amazon
Keeping rainwater clean is not one skill. It is two. The first is maintenance, the small recurring jobs that keep a system tidy. The second is inspection, the periodic examination that proves every part still works the way it was built to. This checklist is about the second discipline.
An inspection is a deliberate walk down the full collection path with a critical eye. Roof and gutters, downpipes, first-flush diverter, inlet screens, tank body and seals, level gauge, overflow, pump and pressure tank, distribution piping, and finally the water itself. Each part either passes, needs monitoring, or fails.
The value of a written inspection is the baseline. A photograph and a note from last season let you see a hairline crack widen, a foundation settle a few millimetres, or a screen fray one mesh further. Nothing in a rain system breaks overnight. It drifts, and a regular inspection catches the drift before it reaches the pump.
This checklist runs the inspection zone by zone: catchment and roof, diverter and inlet, tank structure and seal, overflow and drainage, pump and pressure, distribution and leaks, and the water-quality record. For the recurring cleaning tasks see our rainwater harvesting maintenance checklist. Every buyable line links to current options on Amazon.com, and Spare Theory may earn a commission on those links. We never set or verify Amazon's prices.
At a glance
- Inspection is a separate discipline from cleaning. It confirms each part is present, correctly sized and still working.
- Work the system downstream, from roof to tap. Water cannot be cleaner than the first surface it lands on.
- The costly faults hide: a waterlogged pressure bladder, a slow suction leak, a foundation settling under a full tank.
- A dated photograph of each part is the whole point. It lets next season's inspection see a crack grow.
The full list
The same list the builder above ticks. Use it for printing or when JavaScript is off.
Catchment and roof inspection
The water is only ever as clean as the first surface it lands on.
- CORERoof surface checked for rust, broken tiles, overhanging branches and any bird or leaf load Amazon
- CORERoofing material confirmed safe for collection; no asbestos cement, lead flashings or weathered coating Amazon
- Gutters checked for correct fall toward the downpipe and for standing water Amazon
- Downpipe joints and brackets inspected for cracks, splits and a secure fit to the wall Amazon
First-flush and inlet inspection
Confirm the diverter is actually diverting, not quietly bypassing.
- COREFirst-flush diverter confirmed present, its held volume re-checked against the true roof area Amazon
- COREDiverter drain tested: open it and confirm the held volume empties fully and freely Amazon
- Calmed inlet inspected inside the tank to confirm it still directs flow to the floor Amazon
- Leaf screen and tank-inlet mesh checked for tears, sagging and gaps larger than one millimetre Amazon
Tank structure and seal inspection
The tank holds thousands of kilograms. Inspect the body and every opening.
- CORETank exterior walked all the way round for cracks, bulges, weeping seams or UV damage Amazon
- Manhole lid and gasket inspected for a tight seal with no hardening or cracks Amazon
- COREAll openings confirmed mosquito-proof, with no gap a rodent or frog could enter Amazon
- Foundation and ground beneath the tank checked for settlement, erosion or a leaning base Amazon
Overflow and drainage inspection
A full tank needs an honest escape route for the next storm.
- COREOverflow pipe checked for correct size and an unobstructed outlet screen Amazon
- Overflow discharge path confirmed to carry water clear of building footings and the tank base Amazon
- Surge capacity noted before the wet season so a storm is not lost from a full tank Amazon
- Any diversion or pump-out fitted to the overflow tested to confirm it still routes as intended Amazon
Pump and pressure inspection
Test the pump under load. A pump that runs is not always a pump that works.
- COREPump start and stop observed under load for normal pressure, noise and cycling Amazon
- Pressure-tank pre-charge checked; a waterlogged bladder is a hard-to-spot fault Amazon
- Non-return valve and prime confirmed; a pump that loses prime signals a suction leak Amazon
- COREElectrical supply, earthing and RCD protection at the pump tested for safety Amazon
Distribution pipework and leak inspection
The losses that matter are the ones you cannot see at the tank.
- Every accessible joint and fitting inspected for weeping, corrosion and a secure connection Amazon
- COREGround walked along buried runs for unexplained wet patches, sinkholes or lush growth Amazon
- Exposed pipe insulated or shielded against freeze damage for the coming cold season Amazon
- COREBackflow prevention or a break tank confirmed where rainwater meets any mains connection Amazon
Water quality and documentation inspection
An inspection that is not written down is only a memory.
- COREA sample drawn and taste-and-smell checked at the kitchen tap, not only the tank outlet Amazon
- Test-strip readings for pH, turbidity, nitrate and bacteria recorded with the date Amazon
- COREA dated photograph of every component saved so the next inspection can compare Amazon
- A written action list made: pass, monitor or fix, ordered by safety and quality impact Amazon
Inspection is a different job from cleaning
It is tempting to treat upkeep as one thing. Wipe the screen, drain the diverter, clear the gutter, and call the system maintained. That is the cleaning layer, and it is necessary. But cleaning does not ask whether a part is still fit for purpose.
Inspection asks a harder question. Is the diverter still sized for this roof? Is the tank seal still intact? Is the pump still reaching pressure? Is the foundation still level? Those are not tasks. They are verdicts, and each one is either a pass, a watch, or a fail.
The two disciplines run on different clocks. Cleaning is frequent and small. Inspection is twice a year and deliberate. A homeowner who only cleans will keep a tidy system that fails anyway. A homeowner who only inspects will catch faults but drown in avoidable sediment.
This checklist is the inspection half. Carry it with the maintenance routine and the pair covers every realistic failure a rainwater system has.
Bring a clipboard: An inspection without a written record loses its value. Print this list, mark every line pass, watch or fail, and file it. The paper is what makes the next inspection smarter.
Cleaning keeps the system tidy. Inspection proves it still works. Run both, on their own clocks, twice a year at minimum.
Work downstream, never at random
The fastest way to miss a fault is to wander around the tank without a route. Inspect in the direction the water travels. Start at the roof, move to the gutters and downpipe, then the diverter, the inlet screens, the tank body, the overflow, the pump, and finally the pipes and the tap.
This order mirrors the water's own journey. Any defect upstream will show as a symptom downstream, so a clean roof with a plugged diverter explains a dirty tank without anyone blaming the filter. Diagnosing along the path stops you treating the wrong stage.
It also saves repetition. When you inspect the inlet once, you check the mesh, the calmed inlet and the first-flush together. Random walks reopen the same lid three times and still miss the leak in the middle of the run.
A downstream route turns a vague chore into a fixed sequence. Fixed sequences get finished, and finished sequences get recorded.
The five-zone habit: If an hour feels like too much, split it. Catchment and inlet one week. Tank and overflow the next. Pump and pipes the third. Every zone inspected a little more often than you need.
Follow the water from roof to tap. A defect upstream becomes a symptom downstream, so the route tells you which stage is really at fault.
Structure and seal: the tank body itself
The tank is the largest single investment in the system and the one component you cannot easily replace once it is full. Inspect it as a structure, not a container. Walk the whole exterior and look for cracks, bulges, discolouration from UV, and seams that weep after a fill.
Then check every opening. The manhole gasket hardens over a few summers. Vents and overflow screens tear. A millimetre gap at the lid is exactly the gap a mosquito breeds in, and the tank's whole mosquito-protection claim rests on seals you can no longer see clearly.
Finally look at the base. A concrete pad that has eroded at one corner, or ground that has settled after a dry season, shifts the load. A leaning tank is a late-stage warning of a foundation problem that started one wet season ago.
None of this is dramatic. It is a careful look at the body, the lid, the vents and the ground, recorded so next season can compare against today.
The full-tank walk: Inspect the exterior when the tank is full, not empty. A wall that only bows under load is exactly the fault that an empty-tank check misses.
Treat the tank as a structure. Check the body for cracks and bulges, every seal for hardening, and the ground for settlement, then photograph it all.
Power and pressure under load
A pump that hums is not proof a pump is right. The honest test is to watch it work. Open a tap, let the pump start, and time how long it takes to reach pressure. Compare that against last season. A slower ramp is an early, measurable sign of a worn impeller or a dropping suction seal.
Check the pressure tank with a simple tyre gauge while it is depressurised. The pre-charge should sit just below the pump's cut-in. Too low or dead means the bladder has failed, and a failed bladder quietly shortens the pump's life every cycle.
Test the electrical side as a safety item, not a plumbing one. Pump circuits near water must have RCD or GFCI protection, sound earthing and no cracked cable. Press the test button and confirm the circuit drops out.
These three checks, timing, pre-charge and electrical safety, turn the pump from a box that runs into a verified part of the system.
The cut-in note: Write the pump's cut-in and cut-out pressures on the tank. Six months later, the only way to know they have drifted is to have written them down once.
Test the pump under load. Time its pressure ramp, gauge the bladder pre-charge, and trip the RCD. Numbers you record beat a hum that sounds fine.
The leaks you cannot see
Most of a system's water loss happens after the pump, in pipe you cannot watch. A slow leak at a buried joint never drips visibly. It simply makes one strip of lawn greener, or leaves a soft patch that widens after rain. Walk every buried run and look at the ground above it.
Above ground, check every joint and fitting by touch and eye. A hairline crack sweats only under pressure, so inspect after the pump has run, not first thing on a cold dry morning.
Protect the parts the season will test. Exposed pipe needs insulation or shielding before the first frost. A split line in winter is a repair that also drains the tank.
Where rainwater touches a mains supply in any way, confirm the backflow prevention or break tank is fitted and sound. That is not a water-saving check. It is a public-health one, and the inspection is where it gets verified.
The meter test: Close every tap and watch the pump. If it still creeps on and off, water is escaping somewhere between the tank and the house. Find the run before it finds you.
Follow the pipe, not just the tank. Green strips, soft ground and damp joints are the only visible traces of a buried leak.
Write it down: the report and the baseline
The inspection's real product is a record. A photograph of each component, a line of test-strip readings, and a short note saying pass, watch or fix. On its own one report means little. Two reports a year apart are the whole value of the exercise.
Draw the water sample at the kitchen tap, not the tank outlet. The pump, the pipe and the aerator all sit between the tank and the glass, and the household drinks at the tap. Test what people actually consume.
Sort the action list by consequence, not by ease. A failed backflow device or a torn tank seal outranks a cosmetic stain, even when the stain is the thing you noticed first. The point of the verdict column is to make that ranking explicit.
File the report beside last year's. Next season's inspection then starts not with a blank walk but with a promise to check the crack that was there before. That comparison is what turns a chore into genuine fault-finding.
Two reports beat ten memories: Keep the last two dated inspections together and the drift is obvious at a glance. A growing crack, a settling base and a rising nitrate all announce themselves the second you place the pages side by side.
The record is the deliverable. Photographs, readings and a pass or fail verdict, filed against last year's, are what make inspection compound in value.
Inspection zones, pass criteria and priorities
| Zone | Pass looks like | Common fail | Priority |
|---|---|---|---|
| Roof and gutters | Sound surface, free drainage, no hazard material | Corroded flashing, standing water | Quality |
| First-flush and inlet | Drain empties, mesh intact, calmed inlet in place | Plugged orifice, torn screen | Quality |
| Tank body and seals | No cracks, tight gasket, level base | Hardened seal, settling pad | Structural |
| Overflow | Correct size, clear screen, runs away from footings | Blocked outlet, undersized pipe | Storm |
| Pump and pressure | Fast ramp, correct pre-charge, RCD trips | Dead bladder, suction leak | Function |
| Pipework | Dry joints, no wet ground, backflow fitted | Buried leak, missing break tank | Safety |
| Water and record | Clear tap sample, readings logged, photos saved | Undocumented drift | Baseline |
Run the walk top to bottom twice a year. Record a pass, watch or fail for each zone and file the result against the previous inspection.
Key terms
- Pre-charge
- The air pressure held in the empty side of a pressure tank's bladder, set just below the pump cut-in so the pump does not short-cycle.
- Non-return valve
- A one-way fitting on the pump suction that keeps the line primed between runs; when it leaks, the pump loses prime and draws air.
- Calmed inlet
- The internal fitting that releases incoming rain gently toward the tank floor so settled sediment is not stirred back into suspension.
- Break tank
- An open physical gap between a rainwater supply and a mains supply that prevents any backflow of non-potable water into drinking lines.
- Surge capacity
- The empty volume left near the top of a tank so the next heavy rain can be captured or safely overflowed rather than lost at the inlet.
- Baseline photograph
- A dated image of a component taken so a later inspection can compare against it and reveal slow drift such as a widening crack.
Tips and common mistakes
Field-tested tips
- Photograph each component from the same spot and angle every inspection. A series shot from one fixed viewpoint makes a slow change jump out.
- Run the inspection right after a rain for the leak checks. Pressurised, wet joints reveal faults that a cold dry morning hides completely.
- Keep a cheap tyre gauge clipped near the pressure tank. Checking the pre-charge then takes ten seconds and is far more likely to actually happen.
- Do the electrical safety test first, before you put a hand anywhere near the water. Trip the RCD, confirm it cuts out, then continue the walk.
Common mistakes
- Treating cleaning as if it were inspection, and never checking whether a part is still fit for purpose.
- Wandering around the tank without a route, then missing the buried leak halfway down the run.
- Testing water at the tank outlet instead of the kitchen tap, so the pump and pipes never get assessed.
- Skipping the written record, so each inspection starts from memory and no slow drift is ever seen.
Frequently asked questions
How often should a rainwater collection system be inspected?
Twice a year is the practical minimum for a household system. Run one inspection just before the wet season, when surge capacity and the overflow matter most, and one after it, when the diverter and screens have earned the most silt. Add a quick monthly glance at the tap and the visible joints between full walks.
What is the difference between maintenance and inspection?
Maintenance is the recurring work that keeps a system clean, such as clearing gutters, draining the diverter and wiping screens. Inspection is the periodic examination that checks whether each part is present, correctly sized and still working. Maintenance fixes what you can see; inspection finds what is quietly drifting out of order before it fails.
What is the most important thing to check on a rainwater tank?
The seals and the base. A hardened manhole gasket or a torn vent screen lets insects and animals into water the household drinks, and a settling foundation under a full tank can crack the body. Both are invisible on a casual glance, so inspect every opening and walk the ground around the tank each season.
How do I know if my first-flush diverter is working?
Open the drain valve and confirm the held volume empties freely and the orifice clears. A diverter that drains slowly, or not at all, has a blocked orifice and is sending the roof's dirt straight into the tank. Test it as part of every inspection and note the flow, because the failure is silent until the water tastes wrong.
What signs mean a rainwater pump is failing?
Watch for a slow pressure ramp, frequent cycling between runs, a pump that loses prime and draws air, and a pressure tank that feels waterlogged when you check its charge with a gauge. Each points at a specific fault, usually a suction leak, a worn non-return valve or a failed bladder, rather than a dying motor.
Should I record or photograph my rainwater inspection?
Yes, and it is the part most owners skip. A single inspection tells you the current state. Two dated inspections side by side reveal drift, which is where nearly every rainwater fault begins. Photograph each component from a fixed angle and log a pass, watch or fail verdict, then file it against the last report.
About this checklist
- Prepared by
- Spare Theory editorial · research-based
- Last checked
- 2026-10-16
How we choose what earns a spotWe treat inspection as a diagnostic discipline separate from routine cleaning. The zone-by-zone route, the hidden-fault list and the written-baseline recommendation follow established rainwater-system and building-inspection practice. Water-quality sampling guidance aligns with household testing norms, and we defer any potability decision to a laboratory test and local public-health advice. We state no prices, endorse no brand, and mark electrical and structural checks as jobs for qualified professionals where risk warrants it.
Reference basisUS Environmental Protection Agency rainwater harvesting and inspection guidanceCenters for Disease Control and Prevention household water testing recommendations