Lewis Rees

Lewis Rees visits the IIG in Hollywood in the attempt to showcase his dowsing abilities.

IIG On-Site Representatives

Date of demonstration:
March 17, 2012

Lead Investigator:
Spencer Marks

Spencer Marks

Courtesy Brian Hart and Mark Johnson

Source of Contact

On January 23rd, 2012, the Independent Investigations Group in Los Angeles received a Challenge application through our automated system from a gentleman named Lewis Rees from Phoenix, Arizona. Mr. Rees was Facebook friends with one of our members, Anna Bishop, and had been directed to us by her because they had had conversations about his abilities as a water dowser. He had been trained as a dowser seven years before, at the age of 64. Mr. Rees categorized dowsing not as a psychic ability but rather an unknown “natural” ability. 

Dave Richards of the IIG Steering Committee answered Mr. Rees on the same day, and a series of three or four e-mails were then sent between them. Negotiations for a protocol stalled, and the negotiations were then turned over to Spencer Marks, also of the Steering Committee.

Claim and Negotiations

During the early e-mails, Mr. Rees mentioned that he would only use one hand to hold the dowsing rod, and not two, as is the more common practice. Mr. Rees mentioned that it didn’t matter which hand the rod was held in. He claimed when water was detected, the rod would turn inward, toward his body, regardless of where the water was in relation to him. This action matched the motion of most practitioners of dowsing, even though some use two rods which tend to move inward to the body and cross each other.

After two or three e-mails were exchanged with Mr. Rees, it was clear that Mr. Rees was trying to make the protocol much more difficult than it needed to be, with him suggesting that Spencer look for “disturbed ground” near a building that might have a water pipe buried within. Spencer Marks asked Mr. Rees specifically if he could find any hidden water, and Rees assured him that he could, as little as one cup.

In the next e-mail, Spencer asked him if he would be comfortable looking for a gallon of water beneath a cardboard box, as this seemed a bit easier to set up than a cup of water beneath four feet of dirt. Mr. Rees agreed that this would be a simple test of his abilities.

After that, the protocol negotiations went quickly and smoothly, and it was agreed that the IIG would hide a gallon of water beneath one of 15 standard file storage boxes in the Center for Inquiry (CFI) parking lot, the headquarters of the main branch of the IIG. Mr. Rees would have to determine which box the water was hidden inside. IIG volunteers would mark off a distance of at least ten feet in our parking lot between the boxes, and Rees would have three trials in which he would have to find the water with 100% accuracy. This would allow the odds against random chance to be 3,375:1, (15^3) which are approximately the odds (5,000: 1) we require of any preliminary demonstration. If Mr. Rees could find the water under these conditions, he would be eligible to move on to the actual test, which requires beating a minimum 1,000,000:1. This would have been accomplished by running the same test with six trials instead of three.

Mr. Rees would be allowed to pre-dowse the entire parking lot, without boxes, with the empty boxes, and with the gallon of water in a controlled, known spot. After he had satisfied himself that the parking lot offered no background interference with ground water, and that he would be able to detect the water in the gallon jug we had provided, he would move on to the actual demonstration.

The date was set to match the next general meeting of the IIG – Los Angeles, which was scheduled for March 17th, 2012.

Lewis Rees and Jim Underdown

As usual, in our behind-the-scenes discussions about setting up the test for Mr. Rees, we discussed ways to thwart possible cheating. We noted that Mr. Rees could position a confederate somewhere near our parking lot at the Center For Inquiry who could watch to see which box the water was hidden beneath and secretly signal Mr. Rees. To combat this possibility, we decided to put milk jugs beneath all the boxes, filling 14 additional jugs with kiln-dried sand along with the one jug of water. This way, any onlooker would see jugs being placed under all the locations, and (hopefully) not be able to determine which was the water jug. To insure a double-blind test, the location of the water jug would be determined at the time of the demonstration by an IIG volunteer picking a number (one through 15) from a hat, then placing the water beneath the box with the corresponding number. Once the first team placed all the water and sand jugs in the parking lot in the under the designated spots, that team would leave the area and signal a second team to  escort Mr. Rees from inside the building where he was sequestered to the parking lot to begin the demonstration. At no time would he be allowed to touch any of the boxes.

The Test

We picked up Mr. Rees at his hotel on the designated day. At 71, Mr. Rees appeared very physically fit, personable, and with a seemingly genuine belief in dowsing.

On the day of the test, it rained, which unfortunately thwarted our testing plans. Since Mr. Rees had driven from Phoenix to do the test, we offered him the option of moving the demonstration indoors, which he agreed to, as long as he could still pre-dowse the floor for water pipes. Mr. Rees also agreed to placing the boxes less than 10 feet apart, necessary because of the limited indoor space. We decided not to bother with the 14 decoy jugs with sand since our indoor space was secure from outside observers.

We took Mr. Rees to the first floor of CFI where he could look up and actually see the bottom of the second floor. . . the same floor that he would be dowsing on. This was important because we could easily establish that there were no water pipes running along this section of CFI. After the visual inspection, he dowsed the area looking for any problem areas. After identifying a few problem spots, we adjusted the location of the boxes according to his request, and he was satisfied that there were no more areas that would interfere with the test. Finally, we placed a jug of water beneath a box in his full view and allowed him to do a test dowse.

Once Mr. Rees was satisfied that nothing would interfere with a fair test of his dowsing abilities, all extraneous members of the IIG and Mr. Rees were asked to leave the area, leaving only the placement team. Once they’d evacuated, the placement team drew a number from the hat, showed it to the camera that was recording the event, then silently placed the water jug beneath the corresponding box. The placement team left the area, and called to the rest of the IIG that the they were ready as they did so. Everyone returned to the room, including Mr. Rees, who began dowsing the numbered boxes.

Mr. Rees went quickly though the room. When box number three seemed to activate his dowsing rod, he announced very confidently that number three was the location of the water. However, the box that actually contained the water was revealed to be box 14, located at least 15 feet away. Though Mr. Rees had technically failed at this point, since he would have had to complete three consecutive trials successfully, but we had asked him as part of the protocol negotiations to complete all three trials even under these circumstances. Mr. Rees failed to find the water in either of the other two trials.

Possible Explanation

We explained to Mr. Rees that the most probable explanation was the Ideomotor Effect, which allows the human body to adjust very subtly to conditions, especially when the eyes give advance warning of something expected. The Ideomotor Effect can cause slight correcting motions of the muscles under various scenarios, like when using a ouija board, as one example. Mr. Rees seemed to accept the possibility, although he felt that in the past he had tested himself under similar controlled conditions. When asked, it was clear that he had never conducted a double-blinded test himself, and we suggested that subtle clues may have been given off by those that had placed the water for him to dowse. Also, he had only provided four containers for hiding the water during his own testing, thus limiting himself to a 1-in-4 possibility of success during every round strictly by chance.

Mr. Rees was then interviewed by Dr. John Suarez, resident psychiatrist in the IIG, and Mark Edward, a professional magician also of the steering committee. The post–demonstration interview is a standard part of the demonstration, used to determine how the applicant came to believe that they had their power(s), and if IIG’s testing them under  controlled conditions had made them view their powers any differently.


This test does not prove that dowsing itself is impossible, only that Mr. Rees failed to show dowsing ability under controlled conditions. The IIG remains open to testing other professed dowsers that come forward. As of this writing, Mr. Rees has stated that our group ran a fair test, and that he will continue to dowse as well as test his abilities on his own under more rigorous conditions. At this time, we have no idea if Mr. Rees has performed those tests.