That’s not normal. I have a 75gpd RODI unit and change the sediment filter, carbon filter and DI resin about every 1000g. The RO membrane about every 2500g. These numbers are all a guesstimate but I’ll go years without changing the RO membrane. It could be you have it hooked up wrong or maybe your TDS from your house is high. My house tds is 120. And I make about 25g of water a week. Can you take a pic of your unit? Sent from my iPhone using Tapatalk