set terminal png
set output 'sewer.png'
set xdata time
set timefmt "%b %d %H:%M:%S %Y"
set title "Sewer conductivity" 
set ylabel "5 - Volts" 
set yrange [0.8:6]
set xrange [*:*]
set xlabel " "
set grid
set size 1.2 ,0.5
set key top left

plot 'power.720' using 1:(5 - $11) t "Highest Point Inside Pipe" with lines lc rgb "green", \
     'power.720' using 1:(5 - $10) t "Mid-Level Inside Pipe" with lines lc rgb "blue", \
     'power.720' using 1:(5 - $12) t "Lowest Point Inside Pipe" with lines lc rgb "red", \
     'power.720' using 1:(5 - $13) t "Soil Outside Pipe"  with lines lc rgb "black"