This chart compares incoming TDS readings to approximately how many gallons of water you can produce before regeneration of your tank is needed.
TDS
(Total Dissolved Solids) 1/4 Tank
Expected Gallons of Water 1/2 Tank
Expected Gallons of Water 3/4 Tank
Expected Gallons of Water Full Tank
Expected Gallons of Pure Water
50 1,506 3,012 4,518 6,024
100 753 1.506 2,259 3,012
200 376 753 1,129 1,500
300 251 502 753 1,004
400 188 376 564 752
500 150 301 451 602
600 125 251 376 502
700 107 215 322 430
800 93 186 282 376
900 83 167 250 334
1000 75 151 220 302