Looking after your drip irrigation field

remember to do this when you lay a drip irrigation field - drainlayer whangarei

Your drip irrigation field plays a big part in your wastewater disposal system and needs a little TLC to keep it in top operating condition.

It is here that treated effluent from your Secondary Septic treatment tank is dose loaded to the soil. The effluent particles are then treated further by soil bacteria and excess moisture is released into the air through plant transpiration. It’s pretty darn cool, if you ask me.


Your wastewater treament system consists of two parts:

  1. The Treatment Tank (secondary treatment tank), and
  2. The disposal field (we’ll be looking at drip irrigation in this post).

Together, these two systems work effectively to dipose of your household wastewater into the environment.

RELATED POST: How to plant out your drip irrigation field

It’s important to remember that your drip irrigation field is a living environment. The soil is full of nutrients, some pathogens and useful soil bacteria. To keep it operating effectively, there are afew things you need to do:

How to Care for your Drip Irrigation Field

  1. Fence it . You don’t want pets, livestock, people or traffic accessing the fields. This avoids the topsoil becoming too compacted to work effectively (those air pockets in the soil help the bacteria do their job) and keeps pathogens in the soil and not in your house.
  2. Mulch it. A good 100mm depth of mulch laid over the top of your drip irrigation area will keep the gorund moist (the bacteria love that) and stop the annoying grass growing before your plants have time to establish themselves.
  3. Plant it. Plants help get rid of the moisture in the field. The use transpiration to draw moisture up through their roots and it evaporates through their leaves. If you want the technical details, here is a good 5 minute video on transpiration and how it works:)
  4. Service it. Your wastewater system requires regular servicing. Part of this service will include flushing the drip line. At the end of each line, there is a flush valve. This can be opened to, you guessed it, flush out any debris that may be in the line.
  5. Check it. Finally, check it. Take a walk over the field (I know I said no traffic, but this is an exception) and check for any broken lines, soggy areas or pooled water. These will need to be looked at by your service agent when he comes to do his check.

VIDEO: Take a walk along a drip line with me

Drip Irrigation field - Whangarei drainlayer


What is drip Irrigation disposal?

When treated effluent leaves your treatment tank, it is a lot of liquid that has got to go somewhere. A pipe carries it from the tank to an area where drip line is laid in a grid formation over a disposal area. Most drip irrigation we use is called ‘pressure compensating line’. This means that when effluent is pumped to the field, all the little emitters release the same amount at the same time. This ensures a consistent spread of effluent over the same area.

What colour is drip irrigation line?

The irrigation line is ALWAYS PURPLE for wastewater, so if you are digging in the garden, you know what you’ve found. It contains only partially treated effluent, so there are still pathogens in the liquid.

Why do I need a Secondary Treatment Tank

A primary treatment tank (even with an effluent filter) does not treat the effluent as finely as a secondary tank would. This results in larger effluent particles being pumped to the drip irrigation lines. And this means blockages. Lots of blockages. If your soil is clay (as is most of the Whangarei area) then there are only a few wastewater treatment option available to you.

Where can I lay the drip irrigation field?

This is not a DIY kind of thing. Drip irrigation requires a good 150mm of topsoil underneath to work efficiently. You will need to do a soil test to determine where the best place is to lay your line. This soil analysis is part of our Onsite Wastewater Design Process. We will examine your site contours and soil quality as part of the report.

How much drip line do I need?

The size of your irrigation field (and length of drip irrigation lines) depends on how many litres of effluent your system will produce and also the constraints your site may have eg slope or stability issues. We calculate your Design Irrigation Rate based on the number of bedrooms and people living in your home. The more bedrooms, the more drip line needed. On average, a 3 bedroom house will need around 300m of drip line.

How to lay drip line

PLEEEASE don’t lay these willy nilly. I can’t count the number ot times we’ve gone to fix a failed system and the drip line has been moved because Little Johnny needed the space for a trampoline. We can work around this if we know your plans from the start, so let us know if you have preferences for a disposal area.

Here is a basic diagram showing the different components of your drip irrigation system:

Whangarei Drainlayer - drip irrigation layout
Drip Irrigation System – AZ/NZS 1547:2012, pg 167

Wayne Jecentho
Wayne Jecentho
Highly recommend the team at Woods Plumbing and Drainage. We had a new septic system designed by Carey and installed by Zane’s team. The whole process was well communicated and executed. A pleasure to deal with and very professional. Cheers guys.
Nicki Burgess
Nicki Burgess
We are so happy with the job Zane and his team did connecting our property to town sewage. Fast, very efficient and tidy. 100% recommend Woods Plumbing. Andrew Youngs & Nicki Burgess
Eileen Hales
Eileen Hales
Very happy to recommend and place a favourable review for Woods Plumbing & Drainage. Zane and his team sorted our drainage problems quickly and efficiently. He liaised with council and other contractors. Very happy with result and thanks Zane
Zane and his team shifted a sewer line across our build site and set up installation for our build. They were great to deal with, and worked in well with the other contractors. Zane went the extra mile to make sure that everything worked seamlessly with the Council. We can't recommend Woods Plumbing and Drainage highly enough!
Iain Robertson
Iain Robertson
Zane and his team did a fantastic job of installing all the drainage on our extension project. They were polite, efficient, pleasant to work with, communicated with me very well to adjust things as we went along and finally left the site veery tidy. I also thought the price was very reasonable for a top notch job. Would highly recommend them for your drainage needs.
Betsy Duncan
Betsy Duncan
We enjoyed our recent dealings with Zane to convert our septic to main sewer. Zane took charge of all the dealings with Council for us, the job ran efficiently and smoothly. Zane and his team were very polite, accommodating and a pleasure to work with. We would definitely use their services again in the future.
Judy Harrison
Judy Harrison
Very happy with the drainage job Zane and his team did for us - the site was left neat and tidy on completion - thank you
Aaron Kennedy
Aaron Kennedy
Great company to work with.
Glen McKenzie
Glen McKenzie
Excellent. Same day service.

How to connect to the Council sewer network

Most existing Whangarei properties have a sewer connection available for them to connect to. Your connection would have been constructed at ...

Apply for a New Sewer Connection

If no existing Sewer Connection is available for your to connect to, then a Public Utility application will need to be ...

How to stop your home flooding in a storm

The 1 in a 100 year rain event last year had many people stressed out. From falling trees to flooding, we got ...