Frequently Asked Drainage Questions and Answers

Drainage questions Q&A

  1.  How will the drainage engineer get rid of the blockage in my drain?

There are a number of ways in which a blockage drain can become unblocked; the most common methods are rodding jetting and corrosive chemicals.  Each is used for different reasons:

  • Rodding

Rods are a series of long poles with a circular brush at the end, this is able to dislodge soft blockages like nappies, sanitary towels and toilet roll.

  • Jetting

High power water jets are used to blast blockages as well as clean the drain or pipe.

  • Chemicals

In instances of inaccessibility, corrosive chemicals are often used to clear blockages in drains.  A concentration of Sodium Hydroxide, a highly caustic material is used to break down the obstruction.

  2.  What could be the problem with my drains?

Drain blockages can be caused by a number of different things, household items like cans and nappies are just as common as tree roots. There are also pests, typically rats, who have been known to build their nests in drain pipes.

  • Tree roots

Tree roots are attracted to drains as a water source and can sometimes crack the pipes.

  • Fat

Fat and grease that we tip down our sinks, build up in our drains until finally causing an obstruction where the water can no longer flow.

  • Hair

Hair and other foreign objects can build up within a drain and cause an obstruction reducing water flow.

3.  What type of chemicals will the drainage engineer use?

The most common chemical used in drainage management is a concentration of Sodium Hydroxide.   

  1. Why do I need to use an experienced, qualified drainage engineer?

A professional drainage engineer is trained to clear a drain properly, without causing further damage.  They are qualified to use the appropriate equipment and the knowledge to apply certain equipment to a particular problem.  Qualified drainage engineers are able to recognise different types of piping and what they are used for.  Certain types of pipes can need replacing; for example Lead pipe, when discovered needs to be replaced due to its known poisonous.  Always call a professional.  Also unless it is on your personal property it may not be your drain, and may need to be dealt with through the water-board.  A drainage engineer would be the best person to advise you.

  1. Why would the engineer need to use a CCTV survey camera to investigate my drain?

There are few reasons why a CCTV survey may be required.  Often it is because there is a reoccurring blockage in the same drain, a CCTV survey is done to check for broken or collapsed pipes.  Alternatively leaking or displaced joints can be a reason for requesting a survey.

  1. Whose drain is it?

The house deeds should give information about boundary lines and personal drainage systems; though in certain houses there are joint drains, where two households waste flow into a communal drain.  This can occasionally cause problems as the drain is the responsibility of the property–owner on which the drain is situated.   A drainage engineer will only be able to manage a drain that is on the property of the customer.  Most drains that are off property are managed via the water-board.

  1. How do drains break if they are under the ground?

Drains that are under the ground can break for several reasons, tree roots and plants will be one of the most common causes of broken or collapsed drains.  However, this could also be caused by building work, building collapse, local road works or natural wear and tear.  Certain types of pipe only last a number of years before they are no longer viable.


  1. How are the pipes fixed if they are under the ground?

There are a few different solutions to fixing underground pipework, and can be largely dependent on the location of the broken pipe.  One easy solution that is popular in areas of limited access is the use of a polyester resin.  The resin can be used with only one small access point, so has no need of potentially costly construction.

How it all works

  • CCTV is used to inspect the pipework and measure the space so that the correct amount of resin is used.
  • The resin is fed into a felt liner.
  • The liner is compressed into an inversion unit and then fed into one end of the pipe to be relined.
  • The balloon like calibration tube is also fed into the pipe after being compressed into the inversion unit.
  • The inversion unit then fills the Calibration tube with compressed air, forcing the resin into place in the pipe.
  • Both the pressure of the inflated tube and the heat of the air inside it, harden the resin into place.
  • The tube is then deflated and removed.
  • Another CCTV inspection is necessary to ensure the pipe has been relined without any problems.
  1. How do you know where the end of the pipe section is?

The ends of an underground piping section is usually defined by the manhole. 

  1. Whose responsibility is a drain?

The drain or manhole on a property is generally regarded as the property owner’s responsibility, even if it is a shared drain.  If the drain is in the road, or outside of the boundaries of a property then the drain is regarded as being part of the Waterboard’s domain.  If access is needed then permission should be sort directly from the Waterboard.

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