Building On Pipeline Easements (Or Close To)

Previous posts have talked about Sewer and Drain Easements but you build close to or over a pipe on an easement?


You must get permission from the owner of the easement to build on the easement.

Some easement owners won’t permit any building.

However some will allow certain works after a fee is paid.

This fee can amount to several thousand dollars particularly if you want to build right over the sewer.


The minimum costs are likely to be a CCTV survey of the pipe which could cost over a thousand dollars.

Additional costs may include either exposing the pipe and encasing the whole line in concrete, or re-routing the pipe and paying for the cost of establishing a new easement.

Getting the Design Right.

When building close to a buried pipeline, whether the building is in the easement, or close to it, the designer needs to ensure no loads are placed  on the pipe.

To avoid placing any load on the pipe the base of any foundation should be below the zone of influence of the pipe.

This zone of influence starts at the base of the pipe and rises at a slope of 1 in 1 to ground level.

In the diagram above

  • Foundation A is unacceptable The base is inside the zone of influence.
  • Foundation B is acceptable Even though it is the same horizontal distance from the pipe as Foundations A because the base is outside the zone of influence.

The base of the foundation is the lowest point of the foundation, that is the bottom of the slab, In the case of piers the base of the piers.

Building Over the Pipe

Some water authorities do allow building right over a pipe. in that case the base of foundations on both sides of the pipe needs to be outside the zone of influence.

Any beam or slab over the pipe needs to be designed to span between the foundations.


To better understand what you can build see

Restrictions in the Blocks section


Rattling or Thumping Pipes – Cures

These cures relate to general rattling or banging when you turn the tap on.

The various reasons for these noises, and their cures are:

Air in Pipes
Typically occurs in new systems, or after some plumbing alterations. You need to purge the air from the system. To do this

  1. Start at the lowest tap or valve and slowly turn on to full. If there is some spluttering leave on until the water runs smoothly then turn off.
  2. Go to the next lowest tap and repeat the procedure, continue working your way around the house until you reach the highest outlet.
  3. Don’t forget outside taps, toilet cisterns and shower heads.

Steam in Pipes
Can affect solar hot water systems and hydronic heating. Generally means the system is running too hot.

  • For solar systems the first thing is to reduce the temperature for the circulation pump start. This will take the hot water from the panels at a lower temperature. If that doesn’t work it may be the storage tank is too small for the area of panels. If you can’t afford a bigger tank shading the panels on summer days can help.
  • For Hydronic heating systems you will need to lower the boiler thermostat.

Insufficient Fixing of Pipes
Affect all sorts of plumbing systems. May need a combination of four different approaches

  • Pack around any loose pipe clips.
  • Install additional clips between existing clips.
  • Install pipe insulation.
  • For pipes in cavities push foam tube insulation along the pipe so it stops the pipe banging on the walls.

If the problem is a bang when you turn the tap off then you need to see the post on Water Hammer.

Underground Pipes

It’s important to make sure you are getting the right type of pipes and fittings that will be underground… don’t want to be digging up you garden, or paths, in case of blockages.


Some plumbers will want to use, and bury, 90 mm diameter rainwater pipes, basically plastic downpipes.

You need to make sure you are getting as a minimum 100 mm PVC pipes rated as DWV.(Stands for Drainage, Waste and Vent).

The reasons are:

      • The 90 mm pipe is thin walled and can be easily deformed once buried. This means you lose capacity without realising it. The DWV is a much thicker and thus stronger pipe.
      • Although the increase in pipe diameter is fairly small the flow capacity of the larger pipe is over 40% higher. That makes a difference in storm conditions.

Pipes are normally marked at 1m intervals with the type, manufacturer, nominal diameter, material, and the Standards reference (AS/NZS1260).

This is printed on the pipe every 1m.

Protect Underground Pipes

It’s important to protect your underground pipes.

One of the problems during a new house construction is that concrete tend to fill underground pipes, causing blockage.

A hydraulic impact cutter can remove concrete in drains and sewers.

Other problems include leaking or burst pipes caused by corrosion, tree roots, and collapsed pipes.

Roots tend to grow toward the direction of the water so a loose connecting or weak point in the underground pipes triggers tree roots to wrap around them until they burst.

That’s why the design of the pipe system is crucial to ensure a problem-free plumbing.

They should be away from trees and other structures to avoid these problems. 

You can use an experienced plumber to help protect your underground pipes.

A qualified and experienced plumber will detect common leak indicators in the underground pipes and repair them. They’ll test the repair and fill the trench.


Bend refers to a term for any change or offset of direction in the pipes, which includes elbows.

They’re fabricated as per piping specification requirement.

Elbows come in standard or pre-fabricated and are available off the shelf. 

Bends are available in 4 different angles for DFW pipes as follows: 15 degrees, 30 degrees, 45 degrees and 90 degrees.

Although 90 degree bends are available, I would NOT install them underground due to the blockage risk….. If you need a 90 degree change of direction underground:

      • For a drain or a sewer use a junction pit.
      • For a charged (pressure) rainwater system use two 45 degree bends with an inspection ‘T’ in the middle.