diff --git a/definitions/variable/groundwater.yaml b/definitions/variable/groundwater.yaml
index 22bae7d22..fa0300c98 100644
--- a/definitions/variable/groundwater.yaml
+++ b/definitions/variable/groundwater.yaml
@@ -9,6 +9,8 @@
     heads on the top productive aquifer (confined or unconfined).
   sectors:
   - groundwater
+  valid_max: 9000.0
+  valid_min: -100.0
 
 - specifier: wtd
   long_name: Water table depth
@@ -20,6 +22,8 @@
     Depth to the water table below land surface (digital elevation mode, DEM).
   sectors:
   - groundwater
+  valid_max: 5000.0
+  valid_min: -1000.0
 
 - specifier: capillary
   long_name: Capillary rise
@@ -31,6 +35,8 @@
     Upward flux from groundwater to soil (leaving aquifer = negative value).
   sectors:
   - groundwater
+  valid_max: 20000.0
+  valid_min: -20000.0
 
 - specifier: gwdrn
   long_name: Groundwater drainage/surface water capture
@@ -43,6 +49,8 @@
     = negative value. When surface water enters the aquifer, this is positive.
   sectors:
   - groundwater
+  valid_max: 20000.0
+  valid_min: -20000.0
 
 - specifier: gwdrnriv
   long_name: Groundwater drainage/surface water capture from rivers
@@ -56,6 +64,8 @@
     entering the aquifer = positive value.
   sectors:
   - groundwater
+  valid_max: 20000.0
+  valid_min: -20000.0
 
 - specifier: gwdrnlak
   long_name: Groundwater drainage/surface water capture from lakes
@@ -69,6 +79,8 @@
     entering the aquifer = positive value.
   sectors:
   - groundwater
+  valid_max: 20000.0
+  valid_min: -20000.0
 
 - specifier: gwdrnwet
   long_name: Groundwater drainage/surface water capture from wetlands
@@ -82,6 +94,8 @@
     entering the aquifer = positive value.
   sectors:
   - groundwater
+  valid_max: 20000.0
+  valid_min: -20000.0
 
 - specifier: gwdrnspr
   long_name: Groundwater drainage/surface water capture from from springs
@@ -95,6 +109,8 @@
     entering the aquifer = positive value.
   sectors:
   - groundwater
+  valid_max: 20000.0
+  valid_min: -20000.0
 
 - specifier: sgd
   long_name: Submarine groundwater discharge
@@ -107,6 +123,8 @@
     also models without density driven flow can submit this variable.
   sectors:
   - groundwater
+  valid_max: 20000.0
+  valid_min: -20000.0
 
 - specifier: abs
   long_name: Groundwater abstractions
@@ -118,6 +136,8 @@
     Groundwater pumped from the aquifer.
   sectors:
   - groundwater
+  valid_max: 20000.0
+  valid_min: -20000.0
 
 - specifier: absd
   long_name: Groundwater demands
@@ -129,6 +149,8 @@
     Gross water demand
   sectors:
   - groundwater
+  valid_max: 20000.0
+  valid_min: 0.0
 
 - specifier: absirr
   long_name: Groundwater abstractions (irrigation)
@@ -140,6 +162,8 @@
     Same as abs but split into different sectors if available.
   sectors:
   - groundwater
+  valid_max: 20000.0
+  valid_min: 0.0
 
 - specifier: absdom
   long_name: Groundwater abstractions (domestic)
@@ -151,6 +175,8 @@
     Same as abs but split into different sectors if available.
   sectors:
   - groundwater
+  valid_max: 20000.0
+  valid_min: 0.0
 
 - specifier: absind
   long_name: Groundwater abstractions (industries)
@@ -162,6 +188,8 @@
     Same as abs but split into different sectors if available.
   sectors:
   - groundwater
+  valid_max: 20000.0
+  valid_min: 0.0
 
 - specifier: absliv
   long_name: Groundwater abstractions (livestock)
@@ -173,6 +201,8 @@
     Same as abs but split into different sectors if available.
   sectors:
   - groundwater
+  valid_max: 20000.0
+  valid_min: 0.0
 
 - specifier: ret
   long_name: Groundwater return flow
@@ -184,6 +214,8 @@
     Return flow of abstracted groundwater.
   sectors:
   - groundwater
+  valid_max: 20000.0
+  valid_min: -20000.0
 
 - specifier: depl
   long_name: Groundwater depletion
@@ -195,6 +227,8 @@
     Permanent losses from groundwater storage
   sectors:
   - groundwater
+  valid_max: 20000.0
+  valid_min: -20000.0
 
 - specifier: lfn
   long_name: Lateral groundwater flux (net)
@@ -206,6 +240,8 @@
     Net cell-by-cell flow
   sectors:
   - groundwater
+  valid_max: 20000.0
+  valid_min: -20000.0
 
 - specifier: lfrf
   long_name: Lateral groundwater flux (right face)
@@ -217,6 +253,8 @@
     Cell-by-cell flow (right)
   sectors:
   - groundwater
+  valid_max: 20000.0
+  valid_min: -20000.0
 
 - specifier: lfff
   long_name: Lateral groundwater flux (front face)
@@ -228,6 +266,8 @@
     Cell-by-cell flow (front)
   sectors:
   - groundwater
+  valid_max: 20000.0
+  valid_min: -20000.0
 
 - specifier: lflf
   long_name: Lateral groundwater flux (lower face)
@@ -239,3 +279,5 @@
     Cell-by-cell flow (lower) when more than 1 groundwater layer is simulated.
   sectors:
   - groundwater
+  valid_max: 20000.0
+  valid_min: -20000.0