Why a camera cannot close out a leak
Epoxy pipe rehabilitation for leaking pipes has one awkward feature. Video answers questions about shape and surface. It shows a crack, a separated joint, a hole, roots coming through. What it cannot show is whether water is passing through a defect that has been covered over, because a liner that has cured against a leaking joint and a liner that has cured with a channel behind it look identical from inside. In a gravity line running at partial depth, the defect may be above the water level during the inspection entirely. The only way to answer the question is to pressurize the line, or to depressurize it, and watch what happens.
The two directions a sewer leaks
Exfiltration is waste leaving the pipe into the ground. It is the case that damages soil, undermines slabs and eventually shows up as settlement. Infiltration is groundwater entering the pipe, which does nothing to the property but loads the system downstream and, on a lateral, shows up as a line that runs when nothing is being used. Rehabilitation addresses both, because both travel through the same defect, but the tests that prove each are different and a proposal should name which one it is demonstrating.
The tests actually used
- Low pressure air test. The line is isolated with plugs, brought to a modest air pressure and allowed to stabilize, and the time for a specified pressure drop is measured against a table. It is quick, uses no water and is the common acceptance test on new and rehabilitated gravity pipe.
- Vacuum test. The same idea in reverse, drawing the line down and timing the recovery. Used where air pressure is awkward and routinely used on manholes and structures.
- Hydrostatic exfiltration test. The line is plugged and filled to a defined head above the crown, and the drop in level over a set period is measured. Slower and messier than air, and the most direct demonstration that water stays inside the pipe.
- Infiltration test. In a line below the water table, flow arriving at a plugged downstream end is measured against an allowable rate.
- Joint or sleeve testing. A packer isolates a single repaired joint and tests that joint alone, which is the practical method when only one defect was addressed.
What sealed the leak in the first place
Epoxy rehabilitation covers a range of products, and they seal a leak by different mechanisms. A full-length cured-in-place liner replaces the leak path with a continuous jointless wall and is sealed at each end against the host. A sectional sleeve does the same thing over a short length, which is the right scope when the video shows one defect and sound pipe on either side, and epoxy relining in Denver is usually the most economical genuine fix for a single leaking joint. A sprayed or brushed coating is a different product with a thinner wall that relies on adhesion to the host, and while it can seal seepage it is not a structural replacement and should not be presented as one.
Put the test in the contract, not in the conversation. A proposal should name which test will be run, to what standard, over what section, with what pass criterion, and who pays if it fails. Testing agreed after the work is finished rarely happens, and a retained payment tied to a passed test is the most reliable way to make sure it does.
What a failed test usually means
Most failures are not the liner. They are the terminations at each end, the connection at a reinstated branch, or a plug that is not seated. That is worth knowing because a failed first test often produces an argument when it should produce a short investigation. A competent crew isolates sections to find where the loss is occurring, fixes the termination or the reinstatement, and retests. A liner that genuinely failed through its wall is rare and shows itself quickly.
Testing what is around the pipe
A leak that ran for years did something outside the pipe that the pipe test will not detect. Soil washed out through an open joint leaves a void, and the void does not fill itself when the leak stops. Where a leak has been running near a foundation, under a slab or beneath a driveway, the sensible closeout includes a look at the ground as well as the pipe, whether by probing, by a further camera pass after a period of service, or in significant cases by a geotechnical opinion. Understanding how a sectional liner seals a single leaking joint makes it clearer what the video did and did not establish, and verified lining installers serving Denver will raise the question of the surrounding ground rather than waiting to be asked.
The record that settles it
The pre-rehabilitation video with the defect and its footage mark, the post-installation video of the full repaired length, the test record showing the method, the section tested, the readings and the pass criterion, and the material data for whatever was installed. A leak that has been proved closed with a documented test is a settled matter. One that has only been looked at is an opinion.
Common questions in Denver
Can a camera prove that leaking pipes have been fixed?
No. Video shows shape and surface, not whether water passes through a covered defect, and in a gravity line the defect may sit above the flow during the inspection. Proving a leak is closed requires pressurizing or depressurizing the line and measuring.
What test is normally used after epoxy pipe rehabilitation?
A low pressure air test is the common acceptance test: the line is isolated with plugs, brought to a modest pressure, and the time for a specified drop is measured against a table. Vacuum and hydrostatic exfiltration tests are used where they suit the situation better.
What is the difference between exfiltration and infiltration?
Exfiltration is waste leaving the pipe into the ground, which damages soil and undermines surfaces. Infiltration is groundwater entering the pipe, which loads the system downstream. Both travel through the same defect but they are demonstrated by different tests.
What happens if the test fails?
Usually the loss is at a termination, a reinstated branch connection or an unseated plug rather than through the liner wall. The crew isolates sections to locate it, corrects the termination or reinstatement, and retests. Genuine liner wall failures are rare and show quickly.
Does a coating count as a leak repair?
A sprayed or brushed epoxy coating is thin and relies on adhesion to the host, so it can seal seepage but is not a structural replacement. A full-length or sectional cured-in-place liner replaces the leak path with a continuous wall sealed at both ends.