Top-rated septic system installers and replacers.

Get matched with top septic system installers and replacers in Merrimack, NH

Enter your zip and get matched with up to 3 pros

Matching on HomeAdvisor

Share some details icon
Share some details about your home project.
Match with local pros icon
Within moments, match with highly-rated local pros.
Compare quotes icon
Compare quotes and choose the best pro for the job.

Find Septic system installers and replacers in Merrimack

Innovative Septic Solutions

4.59(
27
)
•Approved Pro

Innovative Septic Solutions

4.59(
27
)
•Approved Pro
Customers say: Quality work
12 local quotes requested
40 years of experience

Serving all of Hillsborough and the surrounding counties, the professionals at Innovative Septic Solutions are the go-to, full service septic designers and installers you can trust to get the job done right! Call now for a consultation!

"I was selling a 71 year old home and the inspection revealed a failing septic system. I had called another company as well as Bob snd had opted to use the other company which was local in Merrimack. Sadly I was told it would be 6 to 8 weeks. I could not wait that long since the house needed to be sold before winter. I called Bob and he began the same day! He explained he was also an engineer and could do the required septic design himself. He was able to have the entire job done in 2 weeks and we had a contract to sell before he finished. He was a delight to work with and I woukd recommend this company without any hesitation."

Betty F on October 2025

Serving all of Hillsborough and the surrounding counties, the professionals at Innovative Septic Solutions are the go-to, full service septic designers and installers you can trust to get the job done right! Call now for a consultation!

"I was selling a 71 year old home and the inspection revealed a failing septic system. I had called another company as well as Bob snd had opted to use the other company which was local in Merrimack. Sadly I was told it would be 6 to 8 weeks. I could not wait that long since the house needed to be sold before winter. I called Bob and he began the same day! He explained he was also an engineer and could do the required septic design himself. He was able to have the entire job done in 2 weeks and we had a contract to sell before he finished. He was a delight to work with and I woukd recommend this company without any hesitation."

Betty F on October 2025

Avatar for Septic Designs of NH, LLC

Septic Designs of NH, LLC

4.75(
25
)
•Approved Pro

Septic Designs of NH, LLC

4.75(
25
)
•Approved Pro
Customers say: Terrific value
Recommended by 96% of Angi customers
Recommended by 96% of HomeAdvisor customers
21 local quotes requested

Septic Designs of NH LLC is a Veteran owned small business with BBB accreditation. We take great pride in our work and are not satisfied until you are. We do Septic Designs, Inspections, Tank Replacements, and Septic Repairs. We also clear main sewer lines and do Trenchless Pipe Repair. Which is a NO DIG solution for pipe replacements. Our jetter is also a HEATED jetter for that tough grease or other buildup where you need some extra hot water to really clean the pipe.

"I called every plumber around and Septic Design of NH had the best price to put a camera down the sewer line. Problem was located in no time."

Vickie C on September 2021

Septic Designs of NH LLC is a Veteran owned small business with BBB accreditation. We take great pride in our work and are not satisfied until you are. We do Septic Designs, Inspections, Tank Replacements, and Septic Repairs. We also clear main sewer lines and do Trenchless Pipe Repair. Which is a NO DIG solution for pipe replacements. Our jetter is also a HEATED jetter for that tough grease or other buildup where you need some extra hot water to really clean the pipe.

"I called every plumber around and Septic Design of NH had the best price to put a camera down the sewer line. Problem was located in no time."

Vickie C on September 2021

Avatar for Terraform Site Contracting, Corp.

Terraform Site Contracting, Corp.

5.00(
5
)
•Approved Pro

Terraform Site Contracting, Corp.

5.00(
5
)
•Approved Pro
Customers say: Quick response
20 years of experience
Free onsite estimate

We pride our company on reliability, great communication, integrity, and quality work. We are experts in our trade and will do our best to keep you as educated as we can on your particular task or project. We look forward to earning your business!

"Tim was excellent to work with. He was quick to respond and quote. Tim handled all the details, coordinating with the Plumbers, Designers, and Permits. While installing the Septic system, he was also hired to do some grading of the property and install a foundation for a large addition. His quotes were fair, he stayed on budget, and his subcontractors were excellent. Most importantly he answered all of my concerns and questions throughout the job. I will definitely recommend his company. "

Thomas G on October 2025

We pride our company on reliability, great communication, integrity, and quality work. We are experts in our trade and will do our best to keep you as educated as we can on your particular task or project. We look forward to earning your business!

"Tim was excellent to work with. He was quick to respond and quote. Tim handled all the details, coordinating with the Plumbers, Designers, and Permits. While installing the Septic system, he was also hired to do some grading of the property and install a foundation for a large addition. His quotes were fair, he stayed on budget, and his subcontractors were excellent. Most importantly he answered all of my concerns and questions throughout the job. I will definitely recommend his company. "

Thomas G on October 2025

Corriveau Construction Company

5.00(
5
)
•Approved Pro

Corriveau Construction Company

5.00(
5
)
•Approved Pro
Customers say: Quick response
22 local quotes requested
53 years of experience

Bob has been in business for 50 years. Started working on his own property and was disappointed in the quality of other people's work so he decided to go leave a career in electronics sales and into business himself.Became a career in building and developing.Built subdivisions.Built roads and all site work for new homes.

"This is the best construction pro I had in my life. If there is anyone's looking for the best construction crew this company is the best. I've never had anyone in my life as good as Corriveau construction company. They went beyond and above what I expected. "

Bill A on September 2025

Bob has been in business for 50 years. Started working on his own property and was disappointed in the quality of other people's work so he decided to go leave a career in electronics sales and into business himself.Became a career in building and developing.Built subdivisions.Built roads and all site work for new homes.

"This is the best construction pro I had in my life. If there is anyone's looking for the best construction crew this company is the best. I've never had anyone in my life as good as Corriveau construction company. They went beyond and above what I expected. "

Bill A on September 2025

Tom Howe Septic Systems and Excavation

5.00(
6
)
•Approved Pro

Tom Howe Septic Systems and Excavation

5.00(
6
)
•Approved Pro
Customers say: Quick response
Recommended by 100% of Angi customers
Recommended by 100% of HomeAdvisor customers
57 years of experience

A few services we provide are residential and commercial septic pumping, and drain field install/repair. We are conveniently located to serve Hillsborough County. We are licensed, bonded and insured. Tom Howe Septic Systems is a family-owned and operated business that has served the Merrimack area since 1968.

"A"

Tariq S on May 2022

A few services we provide are residential and commercial septic pumping, and drain field install/repair. We are conveniently located to serve Hillsborough County. We are licensed, bonded and insured. Tom Howe Septic Systems is a family-owned and operated business that has served the Merrimack area since 1968.

"A"

Tariq S on May 2022

H. K. White & Son, LLC

5.00(
1
)
•Approved Pro

H. K. White & Son, LLC

5.00(
1
)
•Approved Pro
Customers say: Quick response
Recommended by 100% of Angi customers
Recommended by 100% of HomeAdvisor customers
10 local quotes requested

Welcome to H.K. White & Son, LLC! We are committed to exceeding your expectations. As experts, we will handle your needs with the high quality expertise that your home or business deserves. We offer competitive prices and customer satisfaction is our number one priority. Call us now!

"They were very approachable, and made me feel comfortable as a woman dealing with contractors. Very professional, and on time, even checking in when their day was done. I would say they went above and beyond."

Kathy Y on March 2019

Welcome to H.K. White & Son, LLC! We are committed to exceeding your expectations. As experts, we will handle your needs with the high quality expertise that your home or business deserves. We offer competitive prices and customer satisfaction is our number one priority. Call us now!

"They were very approachable, and made me feel comfortable as a woman dealing with contractors. Very professional, and on time, even checking in when their day was done. I would say they went above and beyond."

Kathy Y on March 2019

Granite State Sewer & Drain Cleaning Co

4.92(
12
)
•Approved Pro

Granite State Sewer & Drain Cleaning Co

4.92(
12
)
•Approved Pro
Customers say: Quality work
Recommended by 91% of Angi customers
Recommended by 91% of HomeAdvisor customers
15 local quotes requested

Granite State Sewer & Drain Cleaning Co is your go-to plumbing and drain cleaning expert in New Hampshire. With our extensive experience and top-notch service, we stand out from the competition. Contact us today for all your plumbing needs! Additional DBAs - Granite State Sewer Pumps, Granite State Sewer & Drain Cleaning Inc.

"good job and reasonable pricing"

David S on September 2025

Granite State Sewer & Drain Cleaning Co is your go-to plumbing and drain cleaning expert in New Hampshire. With our extensive experience and top-notch service, we stand out from the competition. Contact us today for all your plumbing needs! Additional DBAs - Granite State Sewer Pumps, Granite State Sewer & Drain Cleaning Inc.

"good job and reasonable pricing"

David S on September 2025

Roadway Excavators Inc.

5.00(
2
)
•Approved Pro

Roadway Excavators Inc.

5.00(
2
)
•Approved Pro
Customers say: Quick response
Recommended by 100% of Angi customers
Recommended by 100% of HomeAdvisor customers
16 local quotes requested

Roadway Excavators Inc. is committed to excellence in every aspect of our business. We uphold a standard of integrity bound by fairness, honesty, and personal responsibility. Our distinction is the quality of service we bring to our customers. Accurate knowledge of our trade combined with ability is what makes us true professionals. Above all, we are watchful of our customers' interests and make their concerns the basis of our business

"Replaced leech field- he did an excellent job removing my old leech field and replacing it with a better system. From the time I entered the job in homeadvisor (approx 8am) I was called back before noon. We scheduled a site review later that day. From the time I selected Roadway, there was constant progress. Even when the permits were in progress, they were in constant contact to let me know what was going on. When the permits were in order, they worked nonstop until the job was done. Their work was excellent, prompt and neat. Highly recommend."

Russ R on April 2021

Roadway Excavators Inc. is committed to excellence in every aspect of our business. We uphold a standard of integrity bound by fairness, honesty, and personal responsibility. Our distinction is the quality of service we bring to our customers. Accurate knowledge of our trade combined with ability is what makes us true professionals. Above all, we are watchful of our customers' interests and make their concerns the basis of our business

"Replaced leech field- he did an excellent job removing my old leech field and replacing it with a better system. From the time I entered the job in homeadvisor (approx 8am) I was called back before noon. We scheduled a site review later that day. From the time I selected Roadway, there was constant progress. Even when the permits were in progress, they were in constant contact to let me know what was going on. When the permits were in order, they worked nonstop until the job was done. Their work was excellent, prompt and neat. Highly recommend."

Russ R on April 2021

Miller Environmental

No reviews yet

Miller Environmental

No reviews yet
28 years of experience

Family owned and operated

Family owned and operated

...
Showing 1-10 of 445
FAQs for septic system installation and replacement projects in Merrimack, NH

The smallest standard septic system uses a 500-gallon tank, which costs between $875 and $1,150 installed. This size works well for single-occupant dwellings with minimal wastewater production. However, many local regulations specify minimum tank sizes, so check with your building department before committing to this compact option. Some jurisdictions require at least 750 gallons regardless of home size to ensure adequate waste processing capacity.

The installation timeline varies based on site conditions, permit processing, and contractor schedules. The process includes obtaining permits, conducting soil tests, excavation, tank placement, leach field construction, and final connections. Weather conditions, soil challenges, and inspection scheduling can all affect the overall timeline. It's wise to begin planning well in advance of when you need the system operational.

The most economical approach is to install a conventional anaerobic system with a plastic tank. To minimize costs while maintaining legality, obtain multiple quotes from licensed installers, consider scheduling during their slower seasons, and handle basic site preparation yourself. Never skip permits or required testing to save money—illegal installations can result in significant fines and mandatory removal, ultimately costing far more than doing it right initially.

Regular pumping helps prevent system failures and extends operational life. Most small systems require pumping every three to five years, though frequency depends on household size and usage patterns. Pumping services cost between $290 and $530, making this maintenance expense relatively minor compared to potential repair costs ranging from $500 to $2,600 for neglected systems. Establishing a regular maintenance schedule based on your installer's recommendations helps avoid costly emergency services.

The Merrimack, NH homeowners’ guide to septic system installations and replacements

From average costs to expert advice, get all the answers you need to get your job done.

See all articles