A volume reduction occurs on mixing water with 95% ethanol (or IMS). 1 L of 78% ethanol is prepared by adding 821 mL 95% ethanol (or IMS) to 207 mL H2O.
 If using a 1 L volumetric flask, this is best accomplished by placing 821 mL 95% ethanol (or IMS) into the volumetric flask.  Dilute to volume with deionised water.  Mix well.  Check the level and if necessary add more deionised water to bring it back up to the 1 L mark. 

Product Page (K-RINTDF)