4.9 
19 *The Angi rating for Mold Testing And Remediation companies in Walnut, CA is a rating based on verified reviews from our community of homeowners who have used these pros to meet their Mold Testing And Remediation needs.
*The HomeAdvisor rating for Mold Testing And Remediation companies in Walnut, CA is a rating based on verified reviews from our community of homeowners who have used these pros to meet their Mold Testing And Remediation needs.
Last update on August 24, 2026
Serving Walnut, CA and surrounding areas
Approved
In business since 2001
Free estimates
Emergency services offered
"Customer service was excellent and service was on time/efficient. Pricing was competitive as well."
+93
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."
Serving Walnut, CA and surrounding areas
Approved
In business since 1995
Free estimates
Emergency services offered
"A few months ago I used 911 certified mold testing for my home they were referred to me by my plumber. I had a great experience dealing with this company they were very professional and knowledgeable about mold testing. They were also reasonable in their pricing! I highly recommend using this company for mold testing."
Serving Walnut, CA and surrounding areas
Approved
Super Service Award Winner
In business since 2011
Free estimates
Warranties offered
"Not only did Matt and his crew do an excellent job but they went above and beyond their excellent service."
+6
Serving Walnut, CA and surrounding areas
Approved
In business since 2019
Free estimates
Emergency services offered
"Very approachable and the work performed was top notch."
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
Serving Walnut, CA and surrounding areas
Approved
In business since 2018
Emergency services offered
Small jobs welcome
"Did mold testing services for an apartment building."
+71
Serving Walnut, CA and surrounding areas
Approved
Super Service Award Winner
In business since 2021
Emergency services offered
Small jobs welcome
"They were knowledgeable and thorough about mold testing and removal"
Serving Walnut, CA and surrounding areas
Approved
In business since 2006
Free estimates
Emergency services offered
"Original estimate, management and office staff, arrival and completion time, care of customer's property, clean-up and price were all excellent.
"
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."
+9
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