Best Plants for your Wastewater Drainage Field

It sounds easy enough but before you waste a ton of money and time on plants that end up dying, take a minute to read my top tips on planting out your effluent field. 


The Do’s and Don’t for Septic Tanks
Installation of an Integra Wastewater System

Choose the right Plants to start

Not all plants are suitable to be planted in a wastewater drainage field. When we first bought our home, it came complete with a failing septic system. We ended up needing to redo drainage fields and plant them out to help with moisture control. After an expensive trip to Bunnings,  I came home with a stash of plants, only to have to watch them wilt and die over the next few months.

Yes, I had the recommended list of effluent plants on hand, but I thought I could ignore it. I know now why it’s a recommended list.

Effluent friendly plants are hardy and naturally adept to thriving in a moist soil environment. Remember your effluent system will deliver a daily wastewater content of around 1000 litres a day. Plants help remove that moisture out of the ground and into the air via transpiration.

The plants in your disposal field play an important role in keeping your wastewater system working effectively:

  1. They soak up the wastewater and transpire (plant sweat) moisture into the air through the plants foliage.
  2. They absorb nutrients out of the wastewater so that it does not make its way into the underground water table
  3. They protect the disposal field by limiting access to it (no vehicles randomly driving over the field)

List of Recommended Plants to plant in your disposal field

Plants to plant in an effluent disposal field whangareiNative shrubs, trees and ground covers

Kiokio (fern) Blechnum novaezelandiae
Putaputaweta Carpodetus serratus
Sand coprosma (ground cover) Coprosma acerosa
Mingimingi C. propinqua
Coprosma C.repens
Ti kouka, cabbage tree (fast) Cordyline australis
Karaka (large tree) Corynocarpus laevigatus
Tree fuchsia Fuchsia excorticata
Houhere, lacebark (fast) Hoheria populnea
Pukatea (large tree) Laurelia novae-zelandiae
Manuka Leptospermum scoparium
Kawakawa Macropiper excelsum
Puriri (large tree) Vitex lucens

Grass-like plants

Oioi, jointed rush Apodasmia similis
Rengarenga, rock lily Arthropodium cirratum
Rautahi, tussock sedge Carex geminata
Purei, pukio, tussock sedge Carex secta
Toetoe * Cotaderia fulvida
Umbrella sedge Cyperus ustulatus
Turutu, NZ blueberry Dianella nigra
Pepepe, toetoe tuhara Machaerina sinclarii
Harakeke, flax (fast) Phormium tenax

How many plants to plant

As a general rule, it’s recommended to plant 1 plant per 1 metre square. So a 200 metre square disposal field may require up to 200 plants. But this will depend on the size of the mature plant too. When planting smaller grasses you can space them at a smaller 50-75cm distance apart. Medium sized trees up to 3m wide wil need more space to grow, so plant them at 1.2-1.5m apart.

list of Plants to plant in an effluent disposal field whangarei

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