ForHosting KIT · Developer Utilities

Greywater Reuse Water Savings Calculator

This greywater reuse water savings calculator estimates how much potable water a household can avoid consuming when water from showers, basins, or laundry is captured and reused.

● BetaFree · in your browser

Run — free How it works & API

Use it from WebAPIEmailTelegramApp soon

Enter the greywater volume available during a chosen period and the share that the reuse system can successfully deliver. The result reports saved potable water and greywater that remains unrecovered in liters, making the assumptions visible and easy to compare across daily, weekly, monthly, or annual plans.

Start with a volume for one consistent period

Choose a period that matches the decision you are making, then enter the household greywater volume available during that entire period. A daily estimate is useful for checking storage and irrigation demand, while a monthly or annual estimate can support budgeting, conservation targets, or a retrofit proposal. The calculator does not impose a time unit because liters saved follow the same period as the supplied volume. If you enter 450 liters per week, every result is therefore a weekly result. Build the volume from sources that the planned system can actually collect, such as selected showers, bathroom basins, or a washing machine. Do not automatically include toilets, kitchen waste, stormwater, or fixtures that will remain disconnected. When measurements are unavailable, document the occupancy, fixture flow, and usage assumptions behind your estimate. Keeping the source volume realistic matters more than adding false precision, because the calculation cannot correct an inflated supply estimate. Use the same boundaries when comparing different system designs.

Represent real recovery with reuse efficiency

Reuse efficiency is the fraction of collected or potentially available greywater that becomes a useful substitute for potable water. Enter it as a decimal from 0 to 1: zero means none of the stated volume is reused, 0.75 means seventy-five percent is reused, and 1 means all of it is reused. The factor can account for treatment losses, filter backwashing, storage overflow, seasonal mismatch, downtime, and occasions when end-use demand is lower than supply. It should not be treated as an equipment marketing claim unless that claim covers the complete household system and operating pattern. A practical estimate often comes from monitored delivered volume divided by available greywater volume over the same period. For a proposed installation, compare a conservative, expected, and optimistic efficiency while holding the source volume constant. The calculator deliberately rejects values below zero or above one because those values cannot describe a fraction of the available water. This constraint also prevents percentage and decimal notation from being mixed accidentally.

Interpret savings without overstating system performance

The calculator multiplies household greywater volume by reuse efficiency to estimate potable water saved. It also subtracts the saved amount from the available volume to show unrecovered greywater. These two outputs should add back to the entered volume, apart from rounding to six decimal places. The result is a water-balance estimate, not a guarantee of bill savings or regulatory approval. Financial savings depend on local tariffs, fixed charges, sewer billing rules, installation cost, maintenance, and energy consumption. Suitability also depends on permitted end uses, treatment requirements, plumbing separation, storage controls, labeling, and local health rules. Use the result as one transparent input to design and comparison, then have the proposed system reviewed where regulations require it. For ongoing operation, repeat the calculation with metered data and compare periods with similar occupancy and weather. If estimated savings are consistently higher than measured potable-water reductions, revisit collection volume, efficiency, demand matching, leaks, bypass events, and seasonal assumptions before drawing conclusions about performance.

What you can do with it

Compare household retrofit scenarios

Test conservative and expected reuse efficiencies against the same measured greywater supply before selecting a system size.

Set a water conservation target

Convert a weekly or monthly greywater estimate into a clear potable-water reduction target that can later be checked with meters.

Check operational performance

Use recorded available and delivered volumes to quantify savings and identify the portion lost to overflow, downtime, or insufficient demand.

FAQ

What does the calculation cost?

The API price is $0.002 per request. The browser calculator can run the same deterministic calculation locally.

Should reuse efficiency be entered as a percentage?

Enter a decimal fraction from 0 to 1. For example, enter 0.8 for an eighty-percent reuse efficiency.

What time period does the result cover?

It covers the same period as the volume you enter. A daily volume produces daily savings, and an annual volume produces annual savings.

Does saved water equal collected greywater?

Only when reuse efficiency is 1. Treatment losses, overflow, downtime, and limited demand usually make delivered reuse lower than available volume.

Can this estimate predict my water bill reduction?

No. It estimates liters of potable water displaced. Bill effects depend on local usage rates, fixed fees, sewer charges, and how the utility meters consumption.

Why are efficiencies above 1 rejected?

Efficiency describes the reused share of the available volume, so it cannot be negative or exceed the whole amount.

For developers — API access

Everything on this page is available programmatically. This section is for teams who want to wire it into their own systems; everyone else can just use the tool above.

API endpoint

POSThttps://api.kit.forhosting.com/earth/greywater-reuse-savings

Prefer to automate it? One authenticated POST creates the task; the result comes back by webhook or a signed link. The same capability also runs here on the web, by email and from Telegram — and soon from our app too.

Call it from your stack

curl -X POST https://api.kit.forhosting.com/earth/greywater-reuse-savings \
  -H "Authorization: Bearer $KIT_KEY" \
  -H "Content-Type: application/json" \
  -d '{"household_greywater_volume_liters":450,"reuse_efficiency":0.8}'

const res = await fetch("https://api.kit.forhosting.com/earth/greywater-reuse-savings", {
  method: "POST",
  headers: {
    "Authorization": `Bearer ${process.env.KIT_KEY}`,
    "Content-Type": "application/json"
  },
  body: JSON.stringify({
    "household_greywater_volume_liters": 450,
    "reuse_efficiency": 0.8
  })
});
const { task_id } = await res.json();

import os, requests

res = requests.post(
    "https://api.kit.forhosting.com/earth/greywater-reuse-savings",
    headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
    json={
    "household_greywater_volume_liters": 450,
    "reuse_efficiency": 0.8
},
)
task_id = res.json()["task_id"]

<?php
$res = file_get_contents("https://api.kit.forhosting.com/earth/greywater-reuse-savings", false, stream_context_create([
  "http" => [
    "method"  => "POST",
    "header"  => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
    "content" => '{"household_greywater_volume_liters":450,"reuse_efficiency":0.8}',
  ],
]));
$task = json_decode($res, true);

body := bytes.NewBufferString(`{"household_greywater_volume_liters":450,"reuse_efficiency":0.8}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/earth/greywater-reuse-savings", body)
req.Header.Set("Authorization", "Bearer "+os.Getenv("KIT_KEY"))
req.Header.Set("Content-Type", "application/json")
res, _ := http.DefaultClient.Do(req)

Example request

{
  "household_greywater_volume_liters": 450,
  "reuse_efficiency": 0.8
}

Example response

{
  "task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
  "type": "earth.greywater_reuse_savings",
  "status": "queued",
  "_links": {
    "result": "/tasks/tsk_…/result"
  }
}

The API is asynchronous: the call returns a task_id immediately and the result arrives by webhook. Polling is capped at 1 req/s per task.

Pricing

Per request$0.002

Published price — no tokens, no invented credits. A failed task is never charged.

Errors

HTTP	Code	Meaning
`401`	`unauthorized`	Missing or invalid API key.
`402`	`insufficient_balance`	Your balance doesn't cover the task price.
`404`	`unknown_type`	That task type doesn't exist.
`429`	`rate_limited`	Too many requests. Use the webhook instead of polling.

Read the full KIT documentation →