[Tasmota] SR-04 Ultrasonic Tank Level measurement rules

gistfile1.txt

Rule1 ON sr04#distance>0 DO Backlog var1=((((%value%*)-20)-(EM-20))/(EM-20))*-100; var2=(var1*0.01)*LT; event sendval ENDON
Rule1 + ON event#sendval DO publish tele/watertank/LEVEL %var1% ENDON ON event#sendval DO publish tele/watertank/VOLUME %var2% ENDON
Rule1 1

Replace:
-LT with the number of liters
-EM with the distance when the tank is empty.

You will get percentage (level) and number of liters, accurate starting from 60cm deep tanks.
SR-04 (water proof) is recommended for use.