Index: firmware/App/Services/Reservoirs.c
===================================================================
diff -u -rdfb6b6f44bbcfd44e7d55914ee82617c2f50d745 -r9c523a8628bb75b601c048f67d3ef7250f45f547
--- firmware/App/Services/Reservoirs.c	(.../Reservoirs.c)	(revision dfb6b6f44bbcfd44e7d55914ee82617c2f50d745)
+++ firmware/App/Services/Reservoirs.c	(.../Reservoirs.c)	(revision 9c523a8628bb75b601c048f67d3ef7250f45f547)
@@ -43,7 +43,7 @@
 
 #define MAX_RESERVOIR_WEIGHT            10000                                           ///< Maximum reservoir weight in grams.
 
-#define MIN_DRAIN_INLET_PSI_EMPTY       3.0                                             ///< Minimum drain inlet pressure (in PSI) to indicate reservoir is empty while drain pump on.
+#define MIN_DRAIN_INLET_PSI_EMPTY       -3.0                                            ///< Minimum drain inlet pressure (in PSI) to indicate reservoir is empty while drain pump on.
 
 #define RESERVOIR_DATA_PUB_INTERVAL     ( MS_PER_SECOND / TASK_GENERAL_INTERVAL )       ///< interval (ms/task time) at which the reservoir data is published on the CAN bus.