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  • Average homeowner rating star icon4.9
    Average homeowner rating
  • Verified reviews icon19
    Verified mold testing and remediation services reviews

Top-Rated Mold testing and remediation specialists in Walnut - Updated Nov 2026

Avatar for Mold Solutionz 24/7
Mold Solutionz 24/7
4.2(
35
)
Mold & Toxic Material TestMold & Toxic Material Test - For Business

Serving Walnut, CA and surrounding areas

Approved

In business since 1995

Free estimates

Emergency services offered

"I appreciated Nick for his obvious knowledge and experience with remediation. He was the only one to really talk through options of the 5 companies that came. Everyone else said "this is what we need to do". His pricing seemed fair as well (ALL the quotes I got were expensive). I think he was the 2nd lowest quote. If it's an emergency, I'd say Nick is a fine choice. If you have time, I recommend getting a quote from 5 different companies (or more). An extra bonus with Nick is he has recommended contractors who can do the repairs or plumbing (if needed). But he does not push you to use them or make it seem like you have to use them. It is important to note that Nick only does the remediation. So if they need to cut into a wall or tear something out, it will be an additional cost to then repair it. But I could not find a company that did both remediation AND repair that I was comfortable with."
demo
pic 2
Response time11 hrs
Response rate89%
Recommended by89%of homeowners
Avatar for 911 Certified Mold Testing LLC
911 Certified Mold Testing LLC
5.0(
8
)
Mold & Toxic Material TestIndoor Air Quality TestingMold & Toxic Material Test - For Business

Serving Walnut, CA and surrounding areas

Approved

In business since 1995

Free estimates

Emergency services offered

"Kayla is so wonderful to work with. She is so professional and knows her stuff. Iâ ve used her in 2 projects already and my clients and I are extremely satisfied with her service. Her turn around mold air testing is fast. I will definitely recommend her and will continue to use her service."
Response time4 hrs
Response rate93%
1 neighbors recently requested a quote
Avatar for Night And Day Restoration LLC
Night And Day Restoration LLC
5.0(
5
)
Mold & Toxic Material TestIndoor Air Quality TestingMold & Toxic Material Test - For Business

Serving Walnut, CA and surrounding areas

Approved

In business since 2023

Free estimates

Emergency services offered

Night & Day Restoration LLC specializes in water damage restoration and professional mold testing. Whether you're dealing with a leak, flooding, moisture concerns, or suspected mold, our team will assess the situation, explain what we find, and recommend the right next step.\nWe provide water extraction, structural drying, moisture detection, HEPA air filtration, mold air and surface testing, odor treatment, and structural cleaning. Our team is IICRC Water Restoration Technician (WRT) certified, and we pride ourselves on fast communication, detailed documentation, honest recommendations, and treating your home like it’s our own.\n

47 neighbors recently requested a quote
Avatar for First Source Restoration, Inc.
First Source Restoration, Inc.
4.0(
41
)
Mold & Toxic Material TestToxicity and Mold - RemovalIndoor Air Quality Testing+2 more

Serving Walnut, CA and surrounding areas

Approved

In business since 2006

Free estimates

Emergency services offered

"First Source did a great job with mold remediation after flood. Edi and his assistant went above and beyond what I was expecting. Price was in line with other bids. I hope I don’t have to but I would hire them again."
Infrared light
got mold?
Equipment
mold removal
Plastic Containment

+9

Response time3 days
77 neighbors recently requested a quote
Recommended by88%of homeowners
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Mold Testing and Remediation FAQs, answered by experts

The best way to measure moisture levels in drywall is with a moisture meter. Moisture meters feature small probes that you insert into drywall (similar to pushing a pin into the wall). Ideally, you'll take moisture readings at several locations on the wall to get a general idea of the moisture level.

Mold is a blight on your home but over time, can be an extreme health risk, especially for immunocompromised individuals. Depending on the type of mold you’re dealing with, you could even experience neurological symptoms, or in extreme cases, you can be hospitalized. Even a tiny speck of toxigenic mold can cause a whole slew of very serious health issues. Deal with any mold issues immediately. 

Yes, a one-time water leak can cause mold. Depending on the conditions, mold can begin to grow within 12 to 48 hours. The risk increases with the severity of the leak, high humidity, and when water soaks into absorbent materials like drywall. To prevent mold growth, stop the leak immediately and ensure the area is dried completely; running a blower fan for 24 hours is recommended. If you do notice mold, it's best to call a mold removal specialist to address the situation.

Seeing black dots around the air vents is alarming, but don’t worry. It’s probably just a build-up of soot and darkened dust. Soot is just a byproduct of burning organic materials, so it tends to form in the winter months.

Black mold and wood rot are both types of fungi that thrive in damp areas, but they are distinct issues with different consequences. Wood rot specifically refers to the decay of wood caused by fungi, which compromises the wood's structural integrity. Black mold, on the other hand, is a fungus that grows on the surface of materials, including both rotting and non-rotting wood. The primary difference is their impact: wood rot affects the wood's structure, while toxic black mold is a health hazard. Inhaling black mold spores can cause severe respiratory issues, whereas wood rot spores are generally not harmful to people. Because mold can grow on rotting wood, the two issues can be interconnected, but they are not the same.

The Walnut, CA homeowners’ guide to mold testing and remediation services

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