Water Use and Wastewater in the Georgia Basin an indicator of resource sustainability

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DATA SET

The following data are from Environment Canada's, Municipal Water Use Data. The data on wastewater treatment also includes data from the BC Ministry of Water, Land and Air Protection for an additional treatment category called preliminary treatment. As a result some of the wastewater treatment data categorized as primary treatment has been reclassified as preliminary treatment in this indicator. The data are based on survey results voluntarily submitted by individual municipal water and sewage systems within municipal areas (i.e. municipalities greater than 1000 people) serving more than 200 people. The water data include all water sources except private individual ground water supplies. Cautionary Note: Some values submitted from one survey to the next appear to be repeated and appear in the database. Therefore, the database may under estimate the changes in water use and wastewater treatment quantities between surveys. In addition, the number of municipalities reporting varies as does the timing of the survey results submitted within the survey year.

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Table 1. Municipal Water Use in the Georgia Basin

1- From Statistics Canada Census
2 - The population in the municipality served by any water system except private individual groundwater supplies. It does not include population external to the municipality.
3 - The average daily flow of water used (ADF) based on estimates provided by each municipality. It includes water used from all water sources. Water provided to other municipalities is not included.
4 - The water used per capita is the average daily flow of water used from all sources (ADF) multiplied by 1000 ( to convert kilolitres to litres) and divided by the population served by any water system.

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 Table 2. Average Daily Flow (kilolitres/day) for Water Use and Treated Sewage in the Georgia Basin, 1983-99

1 - The average daily flow of water used (ADF) based on estimates provided by each municipality. It includes water used from all water sources. Water provided to other municipalities is not included. 
2 - The average daily flow of treated sewage (ADFTr) based on estimates provided by each municipality. It includes only the volume of sewage which receives treatment.

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1 - The population served by sewers is the population in the municipalities served by any sewer system. It does not include population external to the municipalities.
2 - The population in the municipalities served by any type of wastewater treatment except private individual septic tanks, and/or tile fields. It does not include population external to municipalities.
3 - The population served by wastewater treatment expressed as a percentage of the population served by sewers.
4 - Preliminary treatment involves screening or comminution/grinding and despite the fact it is a very minimal treatment it is a recognized level of treatment in the sewage treatment industry. 
5 - The definitions for the different wastewater treatment levels are given below. Note: Although in the Water Use Database (Environment Canada, 2005b) Waste Stabilization Pond treatment is reported separately, it is included with secondary treatment since it achieves an equal level of treatment. The wastewater treatment levels data reported here were reviewed and approved by the BC Ministry of Water, Land and Air Protection and Environment Canada, Pacific and Yukon Region staff. 

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Table 4. Total Daily Municipal Water Use by Sector (kilolitres per day) for the Georgia Basin, 1991- 2001 ¹

1 - Survey data prior to 1991 were not used in the analysis since many of the municipalities were unable to assign their water use to any of the three sectoral uses.
2 - "System losses " category includes water lost through leakage and unaccounted water uses such as firefighting, flushing pipes or water unable to be assigned to sectoral categories.

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Table 5. Daily Municipal Water Use per Capita (L/day/person) by Sector for the Georgia Basin, 1991- 2001 ¹

1 - The water use per capita per sector was calculated using the amount of water used per sector divided by the municipal population served by a water system.
2 - "System losses " category includes water lost through leakage and unaccounted water uses such as firefighting, flushing pipes or water unable to be assigned to sectoral categories.

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Types of Municipal Wastewater Treatment 

Preliminary Treatment - It is a physical process to remove larger debris by screening or to reduce the size of solid objects and organic matter by comminution/grinding before the wastewater effluent is discharged to the receiving environment. This treatment level is a very minimal level of treatment closer to no treatment than primary treatment but is a treatment level recognized in the sewage treatment industry.

Primary Treatment - It consists of physical or mechanical operations to remove large solid objects by screens (filters) and sediment and organic matter in settling chambers. The objective of this treatment is to produce an effluent quality with a biochemical oxygen demand (BOD₅) not exceeding 130 mg/L and a total suspended solids (TSS) not exceeding 130 mg/L. Note: Septic tanks are considered primary treatment.

Secondary Treatment - It is based on biological processes to remove biodegradable organic matter and suspended solids from sewage using bacteria and other microorganisms. Following this biological treatment, the effluent undergoes settling to remove suspended solids. This treatment level removes some of the phosphorus (8 - 25%) and nitrogen (10 - 30%). It produces an effluent quality with a BOD₅ not exceeding 45 mg/L and a TSS not exceeding 45 mg/L.

Tertiary Treatment - It is an advanced level of treatment to remove constituents of concern including nutrients, toxic compounds, and increased amounts of organic matter and suspended solids. This level of treatment is utilized when the effluent is discharged to a sensitive receiving environment or in water reuse applications. The process can be accomplished using a variety of physical, chemical, or biological treatment processes to remove targeted pollutants.

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References used for the Water Use and Wastewater Indicator: 

• Environment Canada, 2005a. Municipal Water Use, 2001 Statistics. 2004 Municipal Water Use Report. Ottawa, Ontario.
• Environment Canada, 2005b. Municipal Water Use Data. Ottawa, Ontario. (available at http://www.ec.gc.ca/water/en/manage/use/e_data.htm).
• Environment Canada, 2001a. Tracking key environmental issues. Ottawa, Ontario.
• Environment Canada, 2001b. Municipal water use and Municipal wastewater treatment. National Environmental Indicator Series. SOE Bulletin 2001-1. State of the Environment Reporting Program, Environment Canada, Ottawa, Ontario.
• Environment Canada, 2001c. The State of Municipal Wastewater Effluents in Canada. Indicators & Assessment Office, Environmental Conservation Service, Environment Canada, Ottawa, Ontario. 67p.
• Environment Canada, 2001d. Municipal Water Pricing 1991 - 1999. Ottawa, Ontario.

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