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Find the water getting into your sewers before it floods your system

Inflow & Infiltration Detection

RH Borden builds high-density 3D Manhole Virtual Models that pinpoint the exact cracks, joints, and connections letting groundwater and stormwater into your sanitary sewer, so you fix the right asset first.
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3DVirtual manhole modelsZero-entryInspection workflowAI-taggedDegradation analysis

The short answer

What is Inflow and Infiltration?

Inflow and infiltration, or I&I, is clean water entering a sanitary sewer where it doesn’t belong. Infiltration is groundwater seeping in through cracks, defective joints, and deteriorated structures. Inflow is surface or stormwater entering through direct openings such as manhole covers and illicit connections. Both inflate the volume sent to treatment, drive up costs, consume pipe capacity, and can trigger sanitary sewer overflows. Manholes are one of the most common, and most overlooked, entry points.
Manholes are where a large share of I&I gets in — so that’s where we look
Know the difference

Inflow vs. Infiltration

They enter your system differently and behave differently, which is exactly why each one needs to be located at the source rather than measured only at the plant.

Infiltration GROUNDWATER

Slow, steady seepage through structural defects. Often worst when the water table is high.
  • Cracks and fractures in manhole walls and benches
  • Defective or deteriorated pipe-to-manhole joints
  • Failed grout, corroded surfaces, and root intrusion
  • Persistent base flow that quietly raises treatment volume

Inflow STORMWATER

Fast, direct entry during rain events. Tends to spike sharply and overload the system.
  • Manhole frames, covers, and lid perforations
  • Illicit or cross connections and roof downspouts
  • Surface drainage routed into the structure
  • Sudden peaks that contribute to sanitary sewer overflows
Traditional I&I methods

Why traditional I&I methods fall short

Most inflow and infiltration programs run on four tools: smoke testing, manhole inspection, CCTV, and flow metering. Each one is good at what it was built for, and each one finds something real. What none of them tells you is how many gallons a given defect actually contributes. Without that number, repair budgets get spent on whatever was found first instead of on whatever matters most.

Smoke testing

Smoke testing finds defects with a direct path to the surface: open or broken lids, missing cleanout caps, downspouts and area drains tied into the sanitary sewer. Those are real inflow sources, and finding them matters. What it cannot find is anything below the surface or below the water table, which is where a large share of infiltration lives. It is weather dependent and performs poorly in wet or cold conditions, a real limitation given that wet weather is exactly when I&I shows up. It requires public notification, and smoke entering a building causes alarm. And it is a snapshot: it tells you a defect existed on the day you tested, not how much water came through it during last winter’s storms.

Manhole inspection

Visual manhole inspection tells you the condition of the structure, and structural condition matters. What it does not do is measure flow. Two manholes can look equally worn and contribute wildly different volumes, and inspection alone gives you no way to tell them apart.

CCTV

CCTV shows you the inside of the pipe and finds cracks, root intrusion, and offset joints. For structural condition, it is genuinely useful. But a visible crack is not the same as a quantified leak, and running CCTV across a large system is slow and expensive relative to the amount of pipe it covers.

Flow metering

Traditional flow metering measures how much water is moving past a single point. That tells you a basin has excess flow, which is worth knowing. It does not tell you where inside the basin the water is entering, and that is the question you actually need answered before you can spend a repair dollar with confidence.

What measurement changes

Every method above finds defects. BASINiQ measures contribution. That difference matters because inflow and infiltration follows a power law: in many systems, eighty percent or more of the I&I comes from twenty percent or less of the defects. A sensor network across the collection system shows which basins respond to rainfall and by how much, then narrows the source to specific structures. At that point, smoke testing, CCTV, and manhole inspection become targeted confirmation steps on a short list of suspects instead of system-wide searches. Finding every defect is not the goal. Finding the few that matter is.
Costs and impact

What an I&I assessment costs

What an I&I assessment costs

For a thirty thousand foot basin, a traditional I&I assessment using CCTV and flow metering runs roughly one hundred thousand to one hundred fifty thousand dollars, based on pricing from multiple engineering firms. A BASINiQ assessment of the same basin costs around sixty thousand dollars and returns more precise results.

The comparison

Traditional assessmentBASINiQ
Cost for a 30,000 foot basin$100,000 to $150,000Around $60,000
MethodsCCTV, flow metering50 to 70 radar level sensors
What you get backDefect locationsDefect locations plus how much water each one contributes

Roughly ten times the speed at half the cost.

For a deeper look at how BASINiQ quantifies I&I costs in real systems, see our case study on North America’s largest I&I study using BASINiQ.

What I&I is costing you right now

The assessment cost is the smaller number. For a ten million gallon per day treatment facility running thirty percent I&I, the extra water works out to more than a billion gallons treated per year that did not need to be treated. At typical treatment costs that runs between two point two and five point five million dollars annually in labor, energy, chemicals, and biosolids handling.

Across the industry, thirty five to fifty percent of the water arriving at treatment plants is inflow and infiltration. Close to half of what a plant processes did not need to be there.

The process

How RH Borden Detects I&I in your Manholes

We turn every manhole into an accurate, measurable digital twin, then read its defects in the office instead of guessing in the field.

01

Scan the structure

High-density 3D scanning hardware, such as the CUES Spider, captures the full manhole as a dense point cloud from the surface.

02

Build the Virtual Model

The scan becomes a Manhole Virtual Model you can rotate, zoom, and virtually enter — a permanent digital record of the asset.

03

Analyze conditions

Wall analysis and condition tools surface cracks, joint defects, corrosion, and the openings where water is getting in.

04

Pinpoint & prioritize

Color-coded degradation indicators flag the worst structures so you repair the highest-impact I&I sources first.
Inside the Manhole Virtual Model

What the Model Reveals

Every module works from the same high-density scan, so measurements, conditions, and dimensions all line up with reality.

Manhole conditions

A clear read on the overall state of the structure, from the frame and cover down to the channel and bench.

Manhole wall analysis

Surface-level detail that exposes fine cracks, corrosion, and joint failures that a quick visual inspection misses.

Accurate dimensions

Crosshair and line tools let you measure any depth, diameter, or offset virtually, in real time, with no return trip.

Degradation indicators

AI-assisted red, yellow, and green tags score every manhole for severity, so you can prioritize the structures that need attention first instead of guessing which ones to inspect next.

3D 6K video demo

A high-resolution 3D capture of the manhole interior, showing the same crosshair measurements, wall condition, and severity markers used across every module, viewable from every angle without a return trip to the field.

MVM dashboard

One workspace ties every module together for digital twin asset management across your whole manhole inventory.

Predictive rehab scheduling

Manholes flagged for degradation go on a watch list and get rescanned to track how fast, or whether, conditions are actually changing. Structures that turn out to be stable stay on a longer monitoring cycle instead of getting rehabbed unnecessarily, so budget goes to the manholes that are genuinely getting worse.

Red — severeActive or imminent failure; prioritize for repair
Yellow — monitorEarly degradation; schedule and re-check
Green — soundNo significant defects detected
Why utilities choose MVM

Stop paying to treat water that doesn’t belong in your sewers

Locating I&I at the source turns a guessing game into a ranked repair plan you can budget and defend.

✓ Cut treatment costs

Every gallon of groundwater or stormwater you keep out is a gallon you don’t pump, convey, and treat.

✓ Reduce overflow risk

Removing inflow peaks frees up capacity and lowers the chance of sanitary sewer overflows during storms.

✓ Safer crews

A zero-entry, surface-scanned workflow reduces confined-space exposure while still capturing full detail.

✓ Defensible prioritization

Color-coded condition data shows reviewers and funders exactly why each repair earned its place in the queue.
What clients say

Built for the people who own the system

Mack Straw

The SL-RAT is helping us to support the rapid growth of our collection system.

Mack Straw
Jared Hancock

The SL-RAT service has improved our maintenance program, cut actual costs, and given us much more confidence and trackability concerning the condition of our system.

Jared Hancock
Chuck Gillette, P.E.

This new technology does appear to be valuable in reducing the City’s labor costs by reducing the regular practice of cleaning pipes that may not need to be cleaned... So far this means a reduction of cleaning responsibilities by 10X!

Chuck Gillette, P.E.
James Thomas

Due to the success of acoustic assessments in our city, we are in the process of updating our SSMP to incorporate this into our annual plan for collection system maintenance.

James Thomas
Wade Eva

This is the most amazing device I have seen in 40 years! We can now assess our entire system every year for less than what we were spending to maintain a third of it.

Wade Eva

Great experience

Great to work with, he very informative and responsive. RH Borden has impressed me with their customer service and support.

Paul Swainston

Does what it was avertised to do

Paul Swainston
Joe Hawkes

RH Borden has managed the line and manhole assessment very well. The information is very helpful and saves us time and money.

Joe Hawkes
Cobe Evans

RH Borden has been great to work with we appreciate everything they have done thus far.

Cobe Evans
Don Stonebrink

We are excited to take advantage of this new technology.

Don Stonebrink
Kirk Medina

Well worth the money, we’re very happy to be a customer!

Kirk Medina
Donald Keesler

Working with RH Borden has been exciting, the services they have provided to our city are just what we needed. Would highly recommend them.

Donald Keesler

They were very professional and stayed in contact with the process and results of the job.

Ted Mickelsen

Great customer service and we are excited to understand the condition of our system and use this as an asset management tool.

Ted Mickelsen
Ashton Baker

They have been a great company to work with and very communicative.

Ashton Baker
Jeff Elbert

RH Borden is very easy to work with, very thorough, actionable data at my fingertips.

Jeff Elbert
Answers

Inflow & Infiltration FAQ

I&I is clean water that enters a sanitary sewer where it doesn’t belong. Infiltration is groundwater seeping in through cracks, defective joints, and deteriorated structures. Inflow is surface or stormwater entering through direct openings such as manhole covers, illicit connections, and downspouts. Both increase the volume sent to treatment and can cause sanitary sewer overflows.
Infiltration is groundwater entering slowly through defects and is often steady. Inflow is stormwater entering quickly through direct openings, so it spikes sharply when it rains. Locating both means inspecting the structures where water gets in, and manholes are one of the most common entry points.
We capture each manhole with high-density 3D scanning hardware such as the CUES Spider, then build a Manhole Virtual Model. Engineers virtually enter the structure, measure any dimension, run wall and condition analysis, and locate the cracks, joints, and connections letting water in — all from the office.
Manholes have many joints, frame and cover connections, channels, and benches that degrade over time. Cracks, failed grout, root intrusion, and corrosion all create paths for water to enter. Because manholes are usually inspected less precisely than pipelines, their defects are frequently missed, which makes them a high-value target for I&I reduction.
No. The structure is scanned from the surface and the Manhole Virtual Model is explored virtually. That reduces confined-space entry, improves crew safety, and creates a permanent digital record you can re-measure anytime without returning to the site.
A 3D Manhole Virtual Model for each structure, condition and wall analysis, accurate dimensions, color-coded degradation indicators that flag severe defects, and a prioritized view of which assets need attention first — ready for repair planning, budgeting, and digital twin asset management.
For a typical 30,000 foot basin, a traditional I&I assessment using CCTV and flow metering often runs between $100,000 and $150,000. A BASINiQ assessment of the same basin is typically around $60,000 and returns more precise results by showing not just where defects are but how much flow each one contributes.

See exactly where water is entering your system

Start with a Manhole Virtual Model assessment and get a prioritized, color-coded view of the I&I sources worth fixing first.
Get Started →