About the Water Calculator

This online water calculator is an extension of the original water use calculator provided by the Southwest Florida Water Management District (SWFWMD). It has been customized for Oklahoma and extended with a module to estimate water bills and savings with a 10% use reduction.

All of the city data and javascript code we have added are in city-bill.js. Other changes can be seen in this repository's commit history.

The original calculator from the SWFWMD can be found at https://www.swfwmd.state.fl.us/conservation/thepowerof10/.

The distributable version that we started from can be found at http://www.swfwmd.state.fl.us/dev/SWFWMD_waterusecal/ and downloaded as a zip file.

This project is funded by the National Science Foundation grant OIA-1301789 through OK NSF EPSCoR http://www.okepscor.org/.

Info for maintiners or programmers

City Data Format

City data is located in city-bill.js. An object, cities, is declared at the beginning of the file. The cities object contains a nested object for each city record.

Each city record will look like "CITY NAME":{rates:[], min:}, with a number filled in for the minimum bill and the block information filled in between the square brackets. The comma at the end is important.

One or more rate blocks need to appear between the square brackets. Each rate block will look like {rate_k:, startgal:, endgal:}, with numbers filled in for each of the fields. The field rate_k represents the rate per 1000 gallons and the fields startgal and endgal represent the beginning and end of the rate block measured in gallons. The endgal value on the highest block rate should be set to Infinity without quotes.

Here's an example city record:

"ATLANTIS":{rates:[{rate_k:1.23, startgal:0, endgal:5000}, {rate_k:2.34, startgal:5000, endgal:Infinity}], min:12.00},

In this example, the city Atlantis has a minimum bill of $12.00, a first block rate of $1.23 per 1000 gallons up to 5000 gallons, and a second block rate of $2.34 per 1000 gallons for everything over 5000 gallons.

Here's another example with a different billing scheme:

"MINAS MORGUL":{rates[{rate_k:3.75, startgal:2000, endgal:Infinity}], min:25.00},

In this example, the city Minas Morgul has a minimum bill of $25.00 which includes the first 2000 gallons. We can represent this by omitting the rate entirely (as shown) or by including an explicit rate block like this: {rate_k:0, startgal:0, endgal:2000}.

Here's an example declaration of the cities object with three cities:

var cities = {
    "ATLANTIS":{rates:[{rate_k:1.23, startgal:0, endgal:5000}, {rate_k:2.34, startgal:5000, endgal:Infinity}], min:12.00},
    "MINAS MORGUL":{rates[{rate_k:3.75, startgal:2000, endgal:Infinity}], min:25.00},
    "MINAS TIRITH":{rates:[{rate_k:5.66, startgal:0, endgal:5000}, {rate_k:6.72, startgal:5000, endgal:10000}, {rate_k:7.05, startgal:10000, endgal:Infinity}], min:23.00},
};

Creating City Records from a Spreadsheet

Most of the city water rates are derived from data provided by the Oklahoma Municipal League (OML). The OML data shows a minimum charge and costs for 5,000 gallons, 10,000 gallons, 50,000 gallons, and 200,000 gallons. From this, we derived four block rates: 0-5,000 gallons, 5,000-10,000 gallons, 10,000-50,000 gallons, and >50,000 gallons.

The block rates were provided to me in a spreadsheet with the first row containing column headers. Column 1 (A) contains city names; columns 4-7 (D-G) contain the four block rates; column 8 (H) contains the mininumum bill.

I exported the spreadsheet to tab-delimited text (e.g. water-rates.tsv) and used an awk script to convert the data into javascript objects.

awk -F"\t" 'FNR > 1 && $4 != "" {gsub(/\$/,"",$0); gsub(/Average costs/,"Oklahoma Average",$1); if($5=="") $5=$4; if($6=="") $6=$5; if($7=="") $7=$6; printf("\t\"%s\":{rates:[{rate_k:%f, startgal:0, endgal:5000}, {rate_k:%f, startgal:5000, endgal:10000}, {rate_k:%f, startgal:10000, endgal:50000}, {rate_k:%f, startgal:50000, endgal:Infinity}], min:%f},\n",$1,$4,$5,$6,$7,$8);}' water-rates.tsv

Then I copied the output on the screen and pasted into the cities object in city-bill.js. (And moved the Oklahoma Average line to the top of the object so it would appear first in the drop-down list.)

Some more explanation

The awk script above is hard to read, so I'll present it here as a script file with explanatory comments called make_city_js.awk. You would run the awk script file with a command like this:

awk -F "\t" -f make_city_js.awk water-rates.tsv

make_city_js.awk:

# Skip the first line and any lines where column 4 is blank
FNR > 1 && $4 != "" {

    # Remove dollar signs from the entire line
    gsub(/\$/,"",$0); 
    
    # Replace "Average costs" in column 1 with "Oklahoma Average"
    gsub(/Average costs/,"Oklahoma Average",$1); 
    
    # If the second block rate is blank, repeat the first rate
    if($5=="") $5=$4; 
    
    # If the third block rate is blank, repeat the second rate
    if($6=="") $6=$5; 
    
    # If the fourth block rate is blank, repeat the third rate
    if($7=="") $7=$6; 
    
    # Print the line in the city data format
    printf("\t\"%s\":{rates:[{rate_k:%f, startgal:0, endgal:5000}, {rate_k:%f, startgal:5000, endgal:10000}, {rate_k:%f, startgal:10000, endgal:50000}, {rate_k:%f, startgal:50000, endgal:Infinity}], min:%f},\n",$1,$4,$5,$6,$7,$8);
    
}