Conserving water can be as simple as what’s in your kitchen sink

There is an ongoing debate on the water efficiency of using dishwashers vs doing dishes manually in the sink. When we talk strictly about water savings, there are plenty of arguments indicating new dishwashers are far more water efficient than doing dishes by hand. Unfortunately, not everyone in society has the financial means to upgrade their dishwasher nor does everyone own their own home and can therefore make decisions about kitchen appliances. More importantly, nearly everyone does some form of manual dishwashing (whether pre-rinsing or washing specialty items that don’t fit in the dishwasher). The universal dish washing strategy, therefore, is washing dishes in the sink, so how can we conserve that water? This article will explain how to do that while using less water AND having the ability to harvest that water for outdoor trees/shrubs and houseplants.

A standard, double-bowl kitchen sink has a functional water capacity on one side of about 22 litres (5.8 gallons). That volume is likely far less than the amount of water used when doing dishes due to pre-rinsing, rinsing, and adding clean water during the task. All of the water used generally flows down the drain and into the sewer system on a daily basis. Two simple strategies to significantly reduce water consumption (and subsequent water loss) is to only do hand-washing once per day and use a sink insert.

If you are a camper, you are very likely familiar with a wash basin. Standard basins have a 12 litre capacity, cost about $5, and fit perfectly (with hand room) in the aforementioned standard small sink. Simply using an insert decreases the functional water volume capacity of a sink by almost 50% and has an added bonus: the water is transportable. Using an insert allows you to capture your pre-rinse, soapy water, and rinse water for use in the landscape during the growing months.

There is concern about the effect of regular dish soaps in the landscape, particularly from a biodiversity perspective. Dish soaps contain fragrances and surfactants that can burn plants and harm beneficial insects. There are biodegradable soaps available (like those from Canadian company Nature Clean) but there is little evidence suggesting they are safer for plants. You may use soapy dishwater on the drip line of well-mulched trees and shrubs with confidence that no damage will occur. Avoid pouring soapy water on leaves of plants or to the drip line of leafy perennials. Certainly do not pour soapy water on plants that contain small, soft-bodied insects and never pour soapy water on plants in full sun. Captured water from pre-rinsing dishes and/or rinsing vegetables and fruit can be used anywhere in the landscape (and THAT water can also be used on houseplants).

Here are the simplified steps:

1. Measure your sink to ensure the water basin you use will fit
2. For ease, consider using a large, sturdy pail like a 5 gallon paint pail to transport daily water to the landscape (do not allow pets, bees, or other wildlife access to the pail). A container with a known volume is also helpful for understanding how much water your outdoor plants are receiving weekly.
3. Place the insert in the sink when washing vegetables/fruit or pre-rinsing dishes
4. Empty insert in large pail when it becomes full or spent.
5. Use inserts for both washing and rinsing water
6. Only use soapy water on the mulched dripline of trees & shrubs and spread the water around to different trees in your yard (trees & shrubs need 1 gallon per foot of height/spread per week for two years after they are planted)
7. Mulch will capture food waste – be careful with pets (dogs may be inclined to dig in the garden) or pour the water through a plant pot with drainage holes full of straw to capture food (which can be put in compost every week). 

A family of four who regularly hand washes dishes can capture 18 litres/5 gallons of used water (rinsing/wash/pet) per day to use on trees and shrubs during the growing season (March – October). When a newly-installed tree requires 3.8 litres/one gallon of water per foot of height per week, that gives you enough water to help establish several trees per year as well as support your existing forest. Furthermore, if you capture the water from washing fruit and vegetables, you can use that for your houseplants as well! If you have a backyard composter and store leaves for the winter (to use as mulch in the spring or to mix as a carbon source with kitchen scraps), you can also capture some of your winter wash water to wet down the leaves if there is limited precipitation to decrease your backyard fire risk. 

In Lethbridge, where we live in a semi-arid climate and have experienced several years of drought, using wash and rinse water from your kitchen sink is a great way to support the growth of resilient trees and shrubs in your backyard! Water conservation starting in your kitchen sink!