Inflow & Infiltration Studies
Find where stormwater and groundwater enter the sewer, and how much, so investment goes where it counts.
At a glance
- 6 to 12 weeksA typical short-term study, through wet weather
- Every 1 to 5 minutesLogging that captures storms and the daily pattern
- ATEX and IECExIntrinsically safe equipment for live networks
- Rain gauges in the catchmentEach response tied to the rain that caused it
Stormwater and groundwater in the sewer is one of the most expensive problems a council or utility can have, and one of the hardest to see. Finding it is what we do best.
Industry data suggests inflow and infiltration (I&I) can make up half the flow in an older network during a storm. Left alone, it hides the system’s true capacity and muddies the hydraulic model. Pipes and plants end up too big or too small.
We measure where the water gets in and how much, so your money goes to the repairs that make the biggest difference.
Why I&I matters
Results from the field
Twenty short-term flow meters and on-site rain gauges showed three subcatchments carried 65% of the I&I. Capital went into relining and inflow reduction instead, and peak wet weather flows fell 35% within two years.
Our I&I services
- Find the sources
Flow meters and rain gauges across the catchment show which subcatchments let the water in, and how much.
- Watch it happen
Intrinsically safe meters report over 4G, so you see each storm’s response as it happens.
- Plan the fix
A repair plan built on your own data, with subcatchments ranked by how much water they let in.
- Ongoing support
We keep the monitoring and the fixes working long after the study ends.
What you gain
- Fewer overflowsLess stormwater in the sewer means fewer untreated discharges into local waterways.
- Lower treatment costsEvery litre of rain you keep out of the sewer is a litre you don’t have to pump and treat.
- Assets that last longerA network that isn’t overloaded in every storm lasts longer and fails less often.
- Compliance you can showData that shows you’re meeting environmental regulations and standards.
Short-term and long-term monitoring
Most I&I programs use one or both. The right choice depends on the decision the data has to support.
| Compared on | Short term | Long term |
|---|---|---|
| Typical duration | 6 to 12 weeks, through wet weather | Continuous, across seasons and years |
| What it answers | Where I&I enters, and how much, in each subcatchment | The baseline infiltration load, and how it varies through the year |
| Best used for | Ranking subcatchments for CCTV, manhole surveys and repairs, and storm data for model calibration | Seasonal groundwater infiltration and persistent defects that short studies can miss |
| Capital decisions | Fast evidence for rehabilitation and planning decisions | Whether a capacity upgrade or targeted rehabilitation is better value |
| After the works | A baseline to measure against | Proof of whether past works succeeded |
Monitoring done properly
- High-resolution logging, typically every 1 to 5 minutes, to capture storms and the daily pattern
- Inspections of hydraulics, access and the risk of rag or debris before a site is chosen
- Intrinsically safe equipment for live networks, certified under ATEX and IECEx
- Rain gauges in the catchment, so each wet weather response is tied to the rain that caused it
- QA/QC throughout: data validation, calibration checks and remote telemetry
From data to action
In our experience, and across the water industry, about 20% of a sewer network typically carries 80% of its I&I. Finding that 20% is what makes a program pay back.
- Targeted repairs
The data finds the worst sections for relining, grouting and manhole sealing, so you don’t have to rehabilitate everything.
- Capital works planning
I&I analysis built into long-term asset plans, reducing the need for costly upgrades.
- Performance measurement
Monitoring after the works shows whether each repair delivered.
Common questions
What is the difference between inflow and infiltration?
Inflow is stormwater that enters directly, through cross connections, unapproved private connections and faulty manholes. It arrives quickly during a storm. Infiltration is groundwater that seeps in through cracks, joints and faulty connections. It builds slowly and lingers.
How are the two told apart?
By reading flow against rainfall. Gauges in the catchment and historical climate data separate the fast response of inflow from the slow, groundwater-driven response of infiltration.
How many flow meters does a study need?
It depends on the size of the network and the question being asked. We choose sites by their hydraulics, after inspecting them. One regional council’s study, ahead of a treatment plant upgrade, used 20 short-term flow meters.
What do we receive at the end?
Validated data, and a report that ranks subcatchments by how much they contribute, with a prioritised repair plan. Monitoring after the works shows whether they cut I&I.
How a program runs
From the first call to data you can act on.
- 01
Scope and site selection
Agree what the data has to answer, then choose sites by their hydraulics, not their convenience.
- 02
Install and commission
Trained EDS crews install intrinsically safe instruments, Australia-wide, and check every site before it goes live.
- 03
Monitor and validate
Readings arrive over 4G into FlowSense, with continuous QA/QC and alarms when something changes.
- 04
Report and recommend
Validated data and a report that shows where the problems are and what to fix first, or a feed into your model by API.
Watch inflow and infiltration happen.
Send a storm through a model catchment and watch the hydrograph respond. The gap between measured flow and the dry weather pattern is inflow and infiltration: water that should never have reached the sewer.
Tap or point at the chart to read values, or focus it and press ← →
600 mm pipe. Area velocity meter at the invert; dashed lines are the alarm levels.
An illustrative model of a 600 mm sewer, not live data. Flow is wetted area multiplied by velocity, the way an area velocity flow meter measures it.
Talk to the people who measure it.
Tell us about your network, site or project. A real person from our team will come back to you.