You may want to measure the TDS out of the wall just to eliminate the possibility of a bad membrane or carbon stage. If you're in Houston, you likely have chloramines as well, which may be running through your carbon faster than normal (maybe you don't have it at your house?).I have a 3-way TDS meter on both systems that TDS before DI stage 1, after DI stage 1, after DI stage 2. I have never measured the TDS out of the faucet.