Few things define the NY skyline more notably than the wooden water towers - antique in appearance, but very much alive and in use. Any building higher than 6 stories needs one or an equivalent system to gravity-feed the plumbing system. They’re much cheaper than steel versions. $30,000 versus $120,000. Two companies: Rosenwach Tank Co. and Issek Brothers have the removal and replacement business sewn up. Most tanks hold 10,000 gallons and last 30 years before they rot (they’re not chemically treated to avoid tainting drinking water). Annual inspections and regular cleaning are required by law.