Microsoft unveiled plans Tuesday for a major reconstruction and upgrade of its main Silicon Valley campus in Mountain View, which will modernize the site and contain water-saving, green features.

The unveiling comes as Bay Area tech companies are considering new construction, upgrading existing campuses -- or in Apple's case, settling into newly built facilities -- to create modern, attractive workplaces for employees.

"This project represents a significant investment in our more than 2,000 employees in the San Francisco Bay Area and our commitment to creating the best employee experience in the industry," Kevin Scott, Microsoft's chief technology officer, wrote in a blog post Tuesday.

Redmond, Washington-based Microsoft estimated it will take two years to build the revamped, 643,000-square-foot Mountain View complex, which should be ready to occupy in December 2019.

The company said the campus will be "our smartest, greenest office yet," with highly efficient water use for the site -- located in California's often drought-prone climate.

"One hundred percent of the buildings' non-drinking water will come from rainfall or on-site recycled water," said Pauline Souza, a partner with WRNS Studio Architecture & Planning. "This will be a first in Silicon Valley."

Tech companies in Silicon Valley are dangling enticements in front of recruits or current employees, such as offices with attractive surroundings, near mass transit, restaurants, shopping and outdoor activities.

In downtown San Jose, Google wants to develop a transit-oriented village consisting of 6 million to 8 million square feet of offices that could accommodate 15,000 to 20,000 of its workers. The village would rise near Diridon Station, which already has transit stops for light rail, Caltrain, Amtrak, the ACE Train and buses, and is planned as a stop for BART and a bullet train.