Onterris

What They Do

Water DamageMold Testing

In Their Own Words

Montrose Environmental Group is now Onterris. Onterris provides air quality and emissions services to help organizations meet regulatory requirements, manage environmental risk and improve operational performance. Our air quality services include leak detection and repair (LDAR), source and emissions testing, compliance support, and related environmental monitoring solutions. As a global environmental solutions company, Onterris partners with organizations to solve complex challenges where environmental pressures, regulatory expectations and operational risks intersect. Our mission is to advance the way of life without compromising the integrity of our environment.

Written by the business on its public profile. We have not verified these claims.

Before You Call Onterris

1. Do you take moisture readings every day and will you give me the drying log?
2. Are your technicians certified in water damage restoration?
3. Do you also do remediation? If so, who checks your work?
4. How many air samples will you take, and will you take an outdoor control sample?

Ask for a California contractor license number and look it up with the Contractors State License Board. Also ask for proof of insurance and industry certification for the restoration crew.

How Their Reviews Break Down

Counts from public listings as of September 23, 2026. A handful of reviews says less than a few hundred.

Read This While You Wait

• DIY with careWhat to Do in the First 24 Hours After Water DamageAn hour by hour plan for the first day after water damage. Make it safe, stop the source, document, remove water and start drying before mold can start.
• Call a proMold Testing, When It Is Worth It and How to Read a Lab ReportWhen a mold test is worth paying for, which kind to ask for, why store kits mislead, and how to read spore counts, outdoor controls and a lab report yourself.
• DIY friendlyWasher, Dishwasher, Fridge and Toilet Supply Line LeaksHow washer hoses, dishwasher lines, ice maker tubing and toilet supply lines fail, how to clean up each kind of leak, and how to replace a line yourself.
• DIY with careAttic Mold on Roof Sheathing, Causes and FixesWhy mold grows on attic roof sheathing, how to find the cause, the fixes that stop it for good, and how to tell a cosmetic stain from a roof that needs work.