1250 Gallon Precast Concrete Septic Tanks

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1250 Gallon Septic Tank Overview

Designed to hold 1250 gallons of liquid, this mid-seam style tank offers the ability to run the pipe from the house to either one of its side or center inlets. The same option is available on the outlet of the tank, going out to the leach field from its side or out its middle outlet. Polylok IV closed-end boots are used for the tank’s penetrations, giving a flexible, watertight connection to the pipe entering and leaving the precast structure. Meets all best-practice requirements of ASTM C 1227 & NPCA.

1250 Gallon Septic Tank Details 
Tank dimensions8’ Long 5’8” wide 6’ Tall
Number of bedrooms supportedUp to 4 - Minimum size now required
Pre-assembledYes
Ideal for high water tableNo but our 1250 gallon monolithic septic tank is.
Average retail cost$1125
Number of covers (lids)2
Can come in traffic rated (H20) capacityYes
Concrete strength5,000 PSI
What are its gallons per vertical inch23
Weight11,500 lbs.
Fiber re-enforcedYes
Number of inlets boots (Up to schedule 40 pipe can slide through)3
Height of inlet from bottom of tank to bottom of pipe63”
Number of outlets boots (Up to schedule 40 pipe can slide through)3
Height of outlet from bottom of tank to bottom of pipe60”
Required height of inlet baffle (20% of liquid level)12”
Required height of outlet baffle (40% of liquid level)23”

Frequently Asked Questions

How much does a 1250 gallon precast concrete septic tank cost?

Answer:  The average retail cost for a 1250 gallon precast concrete septic tank is $1125.00.

What is the most common septic tank size?

Answer: In New Hampshire it is the 1250 gallon septic tank.  It is the most common tank specified and used by septic designers.  It is the smallest tank allowed by the NH DES and it is used for up to a four bedroom house.  For additional bedrooms you would add 250 gallons per bedroom.  So a 5 bedroom house would require a 1500 gallon septic tank.

Can you drive over a 1250 gallon septic tank?

Answer: It depends on its design rating.  We manufacturer it in 3 variations: H-10 is for pedestrian traffic with 300 lbs. of live load per square foot plus 3’ of burial depth.  HD is for burial depth up to 5’.  H-20 is for drive over traffic & up to 6’ of burial depth.

Is it ideal for high water table areas?

Answer: Our standard 1250 tank is two pieces, with the seam at the middle.  Our 1250 gallon monolithic septic tank is ideal for high water tables, as the seam is at the very top of the septic tank.  The liquid is below the lid so it can’t leak in or out.  We would recommend using our 1250 gallon monolithic septic tank in situations when needed.

How much does a 1250 gallon concrete septic tank weigh?

Answer: These tanks weigh around 11,500 lbs, but it varies slightly among precast manufacturers depending on the dimensions, wall thickness, floor & top thickness and rebar re-enforcement.

How many bedrooms does a 1250 gallon septic tank support?

Answer: In New Hampshire it supports up to a four bedroom house.  It is the smallest tank size that can be specified on new designs since the rules were revised in 2012.

1250 gallon concrete septic tank drawing.Features/Details*

  • 1250 gallon septic tank is used in up to 4 bedroom systems.
  • Most common tank size used in NH.
  • Smallest tank we recommend to use as a septic tank
  • Is delivered pre-assembled for ease of installation

* Details shown are NH-specific; for details of other states’ specifications please contact us.

You may also be interested in these popular precast concrete septic tanks.

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