---
author: "Franco (nextime) Lanza"
date: 2018-01-19
linktitle: "Grey Water: don't waste it!"
categories: [  "docs", "info" ]
tags: [ "HTW",
        "save_water",
        "water_recycle",
        "grey_water"
      ]
next: /tutorials/github-pages-blog
prev: /tutorials/automated-deployments
title: "Grey Water: don't waste it!"
weight: 10
#authorAvatar: img/logo.png
image: img/greywater.jpg

---

Grey water is all the wastewater you get in your house or office but toilet. 
Wastewater from sinks, showers, baths, washing machines, dish washers and so on is, by definition, grey water.

Grey water in usual home plumbing goes dispersed, and it's an incredible waste as even if isn't potable and polluted by 
detergents and other inquinants it can be usefull and let you save a lot of fresh potable water.

Many info in the wild suggest to use grey water for irrigation, i personally think that isn't a so great idea to use it for that as basically it can contain non eco-friendly detergents and other chemicals that aren't exactly good to be dispersed on the ground.

Of course you CAN filter all the detergents out and get some clean enough water for gardening, but it will be more expensive and you will have to manage to clean and/or change filters every few months. 

But even without using it for irrigation, some good way to recycle remains available.

## Toilet flush: a waste of potable water

An home plumbing usually uses fresh potable water for flushing toilets. You are using potable water to literally flush poo away: what a waste!
Any time you flush the toilet an average of 12 liters of potable water is wasted. According to google an average person flush a toilet 5 times per day:
this make up to 60 liters of potable water per day. 

A good and common suggestion is to put inside the toilet water container a bottle full of something to reduce the capacity of the container and then save up to 2 or 3 liter for every flush. That's a great suggestion, but you will continue to waste 9 to 10 liters in any case.
So, why don't just use grey water instead?

### Others good usages

Other than toilet flush and irrigation, there are few other usage options to reuse grey water with no or little filtering. Just to name one you can use it to wash your car. Those usages will not discussed here at the moment, but maybe in another post i will focus on alternative usages and how to filter it for gardening and irrigation too.

## Grey water for toilet flush: the simple manual way

The cheaper way to do it is to just put a bucket in your shower to collect some of the grey water from there and then use it to flush your toilet by pour over the bucket when needed in the toilet.

This can help to save some water everyday, but it's far to be the best way to do it as you cannot collect more than a little percentage of your grey water that way and obliviously isn't so confortable to do it that way.

## Grey water for toilet flush: a better structured way

By doing some not so expensive plumbing modifications it's usually fairly easy to put a tank somewhere to collect all or almost all the grey water produced in your home in a more efficient and effective way.

A 1000 or 2000 liters tank it's usually the best choice for a 2 to 4 people house with 2 to 5 toilets, and it can effectively help you save more than 300 liters of potable water per day without change the way you are used to use your toilet at all. That's a 9000 liters per month!

Here a simplified schematic of how it works:
![Grey Water for toilet flush](/img/greywater_toilet.jpg)

Collecting the grey water in a tank usually is done by gravity, so, it's just matter to do the right plumbing and put in the right place ( lower than than the lowest drainage you plan to use as a source ) and it's done. A gross filtering of that water can be done, but it isn't really needed usually.

Pushing back the water in the toilet flush container is a little bit more tricky as gravity can't help you on that, so, you will also need a pump to do it.

Usually the best and simple way is to use a pump controlled by low pressure, so, when you push the flush button it will start automatically and then it will stop as soon as the floating element in the container will close the valvle cause the container is full.

A small 1kW pump is more than enough for that, and the power consumption will be moderate as the pump will run only when you flush the toilet for a few seconds.

### Issue number 1: bacterial growth in the tank and bad smelling water

Sorry, not yet written this part, i'll do shortly

### Issue number 2: deposit of lime and other substances in the tank

Sorry, not yet written this part, i'll do shortly

### Issue number 3: Costs:

Sorry, not yet written this part, i'll do shortly

### Hack The Water projects to make it easier

Sorry, not yet written this part, i'll do shortly





