My wife and I found Mammoth Plumbing on yellowpages.com and gave them a call. Our tank water heater was leaking and we called Mammoth at 10:30pm and they were at our home within an hour replacing our heater with a new Rinnai tankless water heater. Their crew had everything installed and cleaned up in a matter of hours. It's only been a few days but we're amazed at how fast our hot water reaches the faucets and we can be washing dishes, clothes, and taking a shower all at the same time and the hot water seems endless. I would recommend Mammoth Plumbing to anyone who wants a top notch plumbing company in Houston.Thank you,Matt & Cindy BowerSpring, TX