diff --git a/core/src/config.jl b/core/src/config.jl
index f09327eac..5fd8692c3 100644
--- a/core/src/config.jl
+++ b/core/src/config.jl
@@ -84,7 +84,7 @@ const nodetypes = collect(keys(nodekinds))
     dtmax::Union{Float64, Nothing} = nothing
     force_dtmin::Bool = false
     abstol::Float64 = 1e-6
-    reltol::Float64 = 1e-3
+    reltol::Float64 = 1e-5
     maxiters::Int = 1e9
     sparse::Bool = true
     autodiff::Bool = true
diff --git a/core/test/allocation.jl b/core/test/allocation.jl
index 2d67ec35b..c4f1183d1 100644
--- a/core/test/allocation.jl
+++ b/core/test/allocation.jl
@@ -1,3 +1,4 @@
+using Test
 import Ribasim
 import JuMP
 using SQLite
diff --git a/core/test/bmi.jl b/core/test/bmi.jl
index 53329af34..780d6a635 100644
--- a/core/test/bmi.jl
+++ b/core/test/bmi.jl
@@ -7,14 +7,15 @@ toml_path = normpath(@__DIR__, "../../generated_testmodels/basic/ribasim.toml")
 @testset "adaptive timestepping" begin
     model = BMI.initialize(Ribasim.Model, toml_path)
     @test BMI.get_time_units(model) == "s"
-    dt0 = 0.011371289f0
+    dt0 = 0.0001269439f0
     @test BMI.get_time_step(model) ≈ dt0 atol = 5e-3
     @test BMI.get_start_time(model) === 0.0
     @test BMI.get_current_time(model) === 0.0
     @test BMI.get_end_time(model) ≈ 3.16224e7
     BMI.update(model)
     @test BMI.get_current_time(model) ≈ dt0 atol = 5e-3
-    @test_throws ErrorException BMI.update_until(model, 0.005)
+    # cannot go back in time
+    @test_throws ErrorException BMI.update_until(model, dt0 / 2.0)
     @test BMI.get_current_time(model) ≈ dt0 atol = 5e-3
     BMI.update_until(model, 86400.0)
     @test BMI.get_current_time(model) == 86400.0
diff --git a/core/test/control.jl b/core/test/control.jl
index 9faac44dd..194c5bd31 100644
--- a/core/test/control.jl
+++ b/core/test/control.jl
@@ -1,3 +1,4 @@
+using Test
 import Ribasim
 using Dates: Date
 
diff --git a/core/test/docs.jl b/core/test/docs.jl
index 8742cdb04..5110358f6 100644
--- a/core/test/docs.jl
+++ b/core/test/docs.jl
@@ -1,4 +1,7 @@
-using Test, Documenter, Ribasim
+using Test
+using Documenter
+using Ribasim
+
 DocMeta.setdocmeta!(Ribasim, :DocTestSetup, :(using Ribasim); recursive = true)
 
 @testset "Doctests" begin
diff --git a/core/test/docs.toml b/core/test/docs.toml
index 0338e085d..fadc0ebbb 100644
--- a/core/test/docs.toml
+++ b/core/test/docs.toml
@@ -25,7 +25,7 @@ dtmin = 0.0         # optional, default automatically determined
 dtmax = 0.0         # optional, default length of simulation
 force_dtmin = false # optional, default false
 abstol = 1e-6       # optional, default 1e-6
-reltol = 1e-3       # optional, default 1e-3
+reltol = 1e-5       # optional, default 1e-5
 maxiters = 1e9      # optional, default 1e9
 sparse = true       # optional, default true
 autodiff = true     # optional, default true
diff --git a/core/test/run_models.jl b/core/test/run_models.jl
index 893034ae1..293a623f1 100644
--- a/core/test/run_models.jl
+++ b/core/test/run_models.jl
@@ -44,7 +44,7 @@ end
     @test model.integrator.sol.u[end] ≈ Float32[519.8817, 519.8798, 339.3959, 1418.4331] skip =
         Sys.isapple() atol = 1.5
 
-    @test length(logger.logs) == 7
+    @test length(logger.logs) == 8
     @test logger.logs[1].level == Debug
     @test logger.logs[1].message == "Read database into memory."
 
@@ -74,7 +74,7 @@ end
     @test model isa Ribasim.Model
     @test successful_retcode(model)
     @test length(model.integrator.p.basin.precipitation) == 4
-    @test model.integrator.sol.u[end] ≈ Float32[469.8923, 469.89038, 410.71472, 1427.4194] skip =
+    @test model.integrator.sol.u[end] ≈ Float32[472.02444, 472.02252, 367.6387, 1427.981] skip =
         Sys.isapple()
 end
 
@@ -198,8 +198,8 @@ end
     @test only(model.integrator.sol(0day)) == 1000.0
     # constant user withdraws to 0.9m/900m3
     @test only(model.integrator.sol(150day)) ≈ 900 atol = 5
-    # dynamic user withdraws to 0.5m/500m3
-    @test only(model.integrator.sol(180day)) ≈ 500 atol = 1
+    # dynamic user withdraws to 0.5m/509m3
+    @test only(model.integrator.sol(180day)) ≈ 509 atol = 1
 end
 
 @testset "ManningResistance" begin
diff --git a/core/test/time.jl b/core/test/time.jl
index 14762374d..69cd408ef 100644
--- a/core/test/time.jl
+++ b/core/test/time.jl
@@ -1,7 +1,7 @@
 using Ribasim
-using SQLite
 using Dates
 using DataFrames: DataFrame
+using Test
 
 @testset "Time dependent flow boundary" begin
     toml_path =
@@ -11,19 +11,22 @@ using DataFrames: DataFrame
 
     flow = DataFrame(Ribasim.flow_table(model))
     # only from March to September the FlowBoundary varies
-    sin_timestamps = 3 .<= month.(unique(flow.time)) .< 10
+    is_summer(t::DateTime) = 3 <= month(t) < 10
 
-    flow_added_1 = filter(
-        [:from_node_id, :to_node_id] => (from, to) -> from === 1 && to === 1,
-        flow,
-    ).flow[sin_timestamps]
+    flow_added_1 =
+        filter(
+            [:time, :from_node_id, :to_node_id] =>
+                (t, from, to) -> is_summer(t) && from === 1 && to === 1,
+            flow,
+        ).flow
     flow_1_to_2 = filter(
-        [:from_node_id, :to_node_id] => (from, to) -> from === 1 && to === 2,
+        [:time, :from_node_id, :to_node_id] =>
+            (t, from, to) -> is_summer(t) && from === 1 && to === 2,
         flow,
-    ).flow[sin_timestamps]
-    @test flow_added_1 == flow_1_to_2
+    )
+    @test flow_added_1 == flow_1_to_2.flow
 
-    t = model.saved_flow.t[sin_timestamps]
+    t = Ribasim.seconds_since.(flow_1_to_2.time, model.config.starttime)
     flow_expected = @. 1 + sin(0.5 * π * (t - t[1]) / (t[end] - t[1]))^2
     # some difference is expected since the modeled flow is for the period up to t
     @test isapprox(flow_added_1, flow_expected, rtol = 0.005)
diff --git a/core/test/validation.jl b/core/test/validation.jl
index 00eb31a7e..971b533fc 100644
--- a/core/test/validation.jl
+++ b/core/test/validation.jl
@@ -1,3 +1,4 @@
+using Test
 using Ribasim
 using Graphs: DiGraph, add_edge!
 using Dictionaries: Indices
diff --git a/docs/schema/Config.schema.json b/docs/schema/Config.schema.json
index 3ecfe60e7..3fccb5fe7 100644
--- a/docs/schema/Config.schema.json
+++ b/docs/schema/Config.schema.json
@@ -51,7 +51,7 @@
                 "dtmax": null,
                 "force_dtmin": false,
                 "abstol": 1.0e-6,
-                "reltol": 0.001,
+                "reltol": 1.0e-5,
                 "maxiters": 1000000000,
                 "sparse": true,
                 "autodiff": true
diff --git a/docs/schema/Solver.schema.json b/docs/schema/Solver.schema.json
index e10fa0894..5d5be176a 100644
--- a/docs/schema/Solver.schema.json
+++ b/docs/schema/Solver.schema.json
@@ -80,7 +80,7 @@
         "reltol": {
             "format": "double",
             "type": "number",
-            "default": 0.001
+            "default": 1.0e-5
         },
         "maxiters": {
             "format": "default",
diff --git a/python/ribasim/ribasim/config.py b/python/ribasim/ribasim/config.py
index 4cbceb969..553e4c340 100644
--- a/python/ribasim/ribasim/config.py
+++ b/python/ribasim/ribasim/config.py
@@ -23,7 +23,7 @@ class Solver(BaseModel):
     dtmax: Optional[float] = None
     force_dtmin: bool = False
     abstol: float = 1e-06
-    reltol: float = 0.001
+    reltol: float = 1e-05
     maxiters: int = 1000000000
     sparse: bool = True
     autodiff: bool = True
@@ -128,7 +128,7 @@ class Config(BaseModel):
                 "dtmax": None,
                 "force_dtmin": False,
                 "abstol": 1e-06,
-                "reltol": 0.001,
+                "reltol": 1e-05,
                 "maxiters": 1000000000,
                 "sparse": True,
                 "autodiff": True,