Tips for Sydneysiders.

Current Dam levels
SourceSCA
Date2012-04-26
% full 96.85
1-week
% change
-0.50
Dams empty date (from 1-year differential)never
Sydney Dam Levels

Current Sydney Water Usage versus inflow statistics (and rainwater tanks)

SUMMARY: Sydney's water usage versus dam inflows
On this page we analyse the relationship between Sydney's dam inflows and Sydney's water usage over the past few years, as well as recent trends over the last few weeks. We also examine how temperature and rainfall effect the usage figures. Helpful for anyone interested in the Sydney water crisis or rainwater tanks, irrigation, grey water tanks, watering systems using rainwater tanks and saving water in general.

The last month's usage and inflow:

Compare this to the same time last year.

What about inflow versus outflow?

A dam's level drops when more water is used (outflow) than flows in (inflow) obviously. This diagram shows cumulative outflow versus cumulative inflow for the entire system, using the SCA daily figures since November 2001. In other words we show for any moment how much water has been used (or entered the dams) since November 2001. Wince Nov 2001, the overall usage has been 5349.39 GL, whilst overall inflow has been 5613.89 GL (compare to the total capacity of Sydney's dams is just under 2400 GL).

Note: when we discuss inflow, we refer to net inflow (i.e. after evaporation is taken into account). This is why the inflow figure can sometimes be below 0 (when evaporation is larger than actual inflows). Although inflow has not equaled outflow for the past few years, it is still very significant. This is one of the reasons why rainwater tanks in Sydney are still useful in drought conditions... it still does rain, just not so much.

The inflow to the dams is inconsistent, however. The following graph displays daily usage and inflows since November 2001. The usage graph shows us that the Summers of 2001/2 and 2002/3 had higher usage, and otherwise there is a slight downward trend on water usage, water saving devices and general water consciousness on the part of consumers. Water restrictions up until level 3 have supposedly reduced water consumption by 12 percent. The large drop in usage in July 2005 corresponded to a fairly wet winter when the (relatively unpopular) desalination plant location was announced. It looks like people take shorter showers when an environmentally relatively unfriendly option is put forward.

A more smoothed out version of this (a one-year rolling average) follows:

Due to the smoothed nature of this graph, the trend is more clear. This is amplified when examined on a year-by-year basis:

When inflow and usage are combined, a figure is arrived at which corresponds to the net gains (or losses) of the dams. This is represented int he following graph (showing Warragamba dam, and the other dams combined). A result greater than 0 represents an increase over a 365 day period for the dams.

How low has Sydney's usage gone in the past few years?

These tables show the record minimum usage for a single day and the record minimum average usage over an entire week.
DateDay Usage ML
2002:01:012054
2003:01:011824
2004:01:011680
2005:01:011585
2006:01:011515
2007:01:011249
2008:01:011428
2009:01:011501
2002:01:022067
2003:01:021490
2004:01:021737
2005:01:021537
2006:01:021899
2007:01:021470
2008:01:021201
2009:01:021414
2002:01:032414
2003:01:031470
2004:01:031627
2005:01:031566

DateWeek Usage ML/day
2002:11:052175
2002:11:062154
2002:11:072157
2002:11:082164
2002:11:092204
2002:11:102250
2002:11:112263
2002:11:122207
2002:11:132181
2002:11:142149
2002:11:152096
2002:11:162028
2002:11:171913
2002:11:181869
2002:11:191894
2002:11:201948
2002:11:211946
2002:11:221889
2002:11:231883
2002:11:241924

How is usage affected by rain and temperature in Sydney?

We have already seen the effects of the 2001/2 and 2002/3 summers on water use, as well as the wet winter of 2005. The following graph compares water usage versus Sydney rainfall on the day before. In times of low rainfall, the usage is dependent on various factors, but when rainfall is high, the water use is quite consistently low. The wettest day (130+mm) of average usage was in 2002 just before a new level of water restrictions came into force.

Temperature also has a large effect on water usage in Sydney. The following diagram shows that low temperatures equate to lower water usage. High temperatures can also match low water usage, however, as rain may occur to lower usage around such days.

The effect of a change in our water usage on Sydney's dam levels?

We have taken the data since November 2001 of Sydney's water usage and dam levels and calculated how full the dams would be under several alternative scenarios:

  • 20% more usage of Sydney water
  • 20% less usage of Sydney water
  • 50% less usage of Sydney water
If everyone had and used rainwater tanks for their irrigation and hand watering of their gardens whenever possible, usage would probably drop by around 20%.

Hypothetical usage since 11.2001Available water% full all dams1 year change GL(%)
20% More 1430.655.41 501.24 (19.41)
As is 2500.5 96.85 583.00 (22.58)
20% Less 2551.898.84 -20.38 (-0.79)
50% Less 2553.298.89 -28.03 (-1.09)

These calculations are of course just on figures since November 2001. When these figures are calculated back to 1998 when the dams were last full, a drop in usage would have produced more dramatic differences in dam levels now.

Sydney dam levels main page
This month dam level statisticsRainfall this week
Trends of Sydney dam levelsUsage and Inflow trends
Firefox Extension (SydDams)Interactive Catchment Map
Dam levels for individual damsSydney Desalination plant impact on dam levels
Reduced Usage impact on dam levelsHow to save water in Sydney
General Information on Warragamba and Sydney's other Dams
Home irrigation/watering systems in Sydney
Old location of Sydney dam levels page
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I-live-in-sydney.com's subsite on Sydney's water is relevant to people interested in conserving water, rainwater tanks, irrigation, plumbing and plumbers. It can also be of interest to people examining water quality and filtering.