diff --git a/CMakeLists.txt b/CMakeLists.txt
index 73436b81..b19f1253 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -41,7 +41,7 @@ endif()
 # compile Var.c as c++
 set_source_files_properties(src/Var.c PROPERTIES LANGUAGE CXX)
 
-add_library(IPhreeqc STATIC src/IPhreeqc.cpp)
+add_library(IPhreeqc src/IPhreeqc.cpp)
 
 target_sources(IPhreeqc
   PRIVATE
diff --git a/litephreeqc/CMakeLists.txt b/litephreeqc/CMakeLists.txt
index 3e75ae34..a51a65ff 100644
--- a/litephreeqc/CMakeLists.txt
+++ b/litephreeqc/CMakeLists.txt
@@ -21,7 +21,8 @@ set(LPQC_SOURCE_FILES
     src/PhreeqcMatrix/Misc.cpp
 )
 
-add_library(litephreeqc STATIC ${LPQC_SOURCE_FILES})
+# add_library(litephreeqc STATIC ${LPQC_SOURCE_FILES})
+add_library(litephreeqc ${LPQC_SOURCE_FILES})
 target_link_libraries(litephreeqc PUBLIC IPhreeqc)
 target_include_directories(litephreeqc PUBLIC
     $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include>
diff --git a/litephreeqc/src/PhreeqcMatrix/Access.cpp b/litephreeqc/src/PhreeqcMatrix/Access.cpp
index 87387d16..9d0729b4 100644
--- a/litephreeqc/src/PhreeqcMatrix/Access.cpp
+++ b/litephreeqc/src/PhreeqcMatrix/Access.cpp
@@ -304,7 +304,7 @@ std::vector<std::string> PhreeqcMatrix::getMatrixTransported() const {
     std::vector<std::string> names;
     
     const std::vector<std::string> to_remove = {
-	"tc", "patm", "SolVol", "pH", "pe"
+	"tc", "patm", "SolVol", "pH", "pe", "MassH2O"
     };
 
     // sols contains all solutes; we must remove { tc, patm, SolVol, pH, pe }
@@ -322,7 +322,7 @@ std::vector<std::string> PhreeqcMatrix::getMatrixTransported() const {
 std::vector<std::string> PhreeqcMatrix::getMatrixOutOnly() const {
     // MDL we must append here selected_output / user_punch
     std::vector<std::string> defaultnames = {
-	"tc", "patm", "SolVol", "pH", "pe"
+	"tc", "patm", "SolVol", "pH", "pe", "MassH2O"
     };
     std::vector<std::string> ret;
     for (auto nm : defaultnames) {
diff --git a/litephreeqc/src/Wrapper/SolutionWrapper.cpp b/litephreeqc/src/Wrapper/SolutionWrapper.cpp
index 9156b382..23302f2d 100644
--- a/litephreeqc/src/Wrapper/SolutionWrapper.cpp
+++ b/litephreeqc/src/Wrapper/SolutionWrapper.cpp
@@ -36,6 +36,7 @@ void SolutionWrapper::get(std::span<LDBLE> &data) const {
   data[5] = solution->Get_soln_vol();
   data[6] = solution->Get_ph();
   data[7] = solution->Get_pe();
+  data[8] = solution->Get_mass_water();
 
   const cxxNameDouble &totals =
       (_with_redox ? solution->Get_totals()
@@ -61,6 +62,7 @@ void SolutionWrapper::set(const std::span<LDBLE> &data) {
   const double &cb = data[2];
   const double &tc = data[3];
   const double &patm = data[4];
+  const double &massh2o = data[5];
 
   for (const auto &tot_name : solution_order) {
     const double value = data[i++];
@@ -71,7 +73,7 @@ void SolutionWrapper::set(const std::span<LDBLE> &data) {
     new_totals[tot_name] = value;
   }
 
-  this->solution->Update(total_h, total_o, cb, tc, patm,
+  this->solution->Update(total_h, total_o, cb, tc, patm, massh2o,
                          _with_redox ? new_totals
                                      : new_totals.Simplify_redox());
 }
diff --git a/litephreeqc/src/Wrapper/SolutionWrapper.hpp b/litephreeqc/src/Wrapper/SolutionWrapper.hpp
index ee909aec..3f7ee8e8 100644
--- a/litephreeqc/src/Wrapper/SolutionWrapper.hpp
+++ b/litephreeqc/src/Wrapper/SolutionWrapper.hpp
@@ -40,10 +40,10 @@ private:
   cxxSolution *solution;
   const std::vector<std::string> solution_order;
 
-  static constexpr std::array<const char *, 8> ESSENTIALS = {
+  static constexpr std::array<const char *, 9> ESSENTIALS = {
       "H",      "O",  "Charge", "tc", "patm",
 
-      "SolVol", "pH", "pe"}; // MDL; ML: only output
+      "SolVol", "pH", "pe",     "MassH2O"}; // MDL; ML: only output
 
   static constexpr std::size_t NUM_ESSENTIALS = ESSENTIALS.size();
 
diff --git a/src/phreeqcpp/Solution.cxx b/src/phreeqcpp/Solution.cxx
index 478911fb..eb5fde44 100644
--- a/src/phreeqcpp/Solution.cxx
+++ b/src/phreeqcpp/Solution.cxx
@@ -1070,7 +1070,7 @@ void cxxSolution::read_raw(CParser &parser, bool check) {
 }
 
 void cxxSolution::Update(LDBLE h_tot, LDBLE o_tot, LDBLE charge, LDBLE tc,
-                         LDBLE patm, const cxxNameDouble &const_nd) {
+                         LDBLE patm, LDBLE massh2o, const cxxNameDouble &const_nd) {
   this->new_def = false;
   this->patm = patm;
   // this->potV = 0.0;
@@ -1083,7 +1083,7 @@ void cxxSolution::Update(LDBLE h_tot, LDBLE o_tot, LDBLE charge, LDBLE tc,
   this->total_h = h_tot;
   this->total_o = o_tot;
   this->cb = charge;
-  this->mass_water = o_tot / 55.55;
+  this->mass_water = massh2o; // o_tot / 55.55; MDL
 
   // this->density = 1.0;
   // this->viscosity = 1.0;
diff --git a/src/phreeqcpp/Solution.h b/src/phreeqcpp/Solution.h
index c659981b..01807b0e 100644
--- a/src/phreeqcpp/Solution.h
+++ b/src/phreeqcpp/Solution.h
@@ -123,7 +123,7 @@ public:
   // void modify_activities(const cxxSolution & original);
   // void Simplify_totals();
   void Update(const cxxNameDouble &nd);
-  void Update(LDBLE h_tot, LDBLE o_tot, LDBLE charge, LDBLE tc, LDBLE patm, const cxxNameDouble &nd);
+  void Update(LDBLE h_tot, LDBLE o_tot, LDBLE charge, LDBLE tc, LDBLE patm, LDBLE massh2o, const cxxNameDouble &nd);
   void Update_activities(const cxxNameDouble &original_tot);
   void Serialize(Dictionary &dictionary, std::vector<int> &ints,
                  std::vector<double> &doubles);