Hypothesis & Overview

This experiment was performed to ascertain the concentration of lead content in the tap water of new houses (less than 10 years old) as compared to houses which are more than 50 years old. These older houses should still be using lead pipe plumbing.

Hypothesis

Older houses use lead pipe plumbing and therefore a higher level of lead content will be detected in the piped water, as compared to newer homes which use PVC pipes
.

Overview

Lead piping

Lead pipes were used in plumbing until the early 20th century. Houses that are older than 50 years of age might still be using lead pipe plumbing. Many new houses use PVC pipes for plumbing, although copper and galvanized piping is equally popular.
Lead pipes cause the level of lead in tap water to increase substantially. Excessive lead content in drinking water can cause hypertension and kidney problems in adults. It also delays mental and physical growth in children. Regulations in the US require the level of lead in drinking water to be less than 15 parts per billion (ppb).

Scientific Terms

Lead, PVC, polyvinyl chloride , ppb (part per billion)

Materials&Procedure

Materials

The materials required for the experiment:

• 10 small bottles to collect water samples.
• Select 5 new houses (less than 10 years old). Each house must be in a different residential area.
• Select 5 old houses (more than 50 years old). Each house must be in a different residential area.
• Select a laboratory to test for lead in the samples. 

Procedure

1. For this experiment, the independent variable is the age of the houses. The dependent variable is the lead content in the water. This is determined by sending the sample for testing in the lab. The constants (control variables) are the amount of water taken as samples, and the laboratory used for testing.
2. Visit the new houses (less than 10 years) and collect the water samples. Houses in different residential areas are selected because they will have a different piping path leading from the water source to the house. Before taking any samples, ask the owner of the house if the plumbing is made of PVC. If he/she is unable to tell you, survey the plumbing in the house to determine if lead, copper or PVC pipes are used. If required, enlist the help of a plumber. If the plumbing is not PVC, find another old house to obtain a sample. Let the tap water run for 30 seconds before taking the water sample. The bottle is immediately labeled and stored safely.
3. Repeat step 2 at 4 more houses.
4. Visit the older houses (more than 50 years old) next. Houses in different residential areas are selected for the same reason above. Before taking any samples, ask the owner of the house if the plumbing has been changed recently. If he/she is unable to tell you, survey the plumbing in the house to determine if lead or PVC pipes are used. If required, enlist the help of a plumber. If the plumbing is not lead, find another old house to obtain a sample.
5. If the plumbing is made of lead, let the water run for 30 seconds before taking a sample of water. Label the bottle and put it aside.
6. Repeat steps 4 to 5 at 4 more houses.
7. When all 10 samples are collected, send the 10 bottles to an independent laboratory to test for the level of lead content.

Observation

The results show that many houses which are more that 50 years of age have lead pipes and where they do, a higher dosage of lead is found in the water. Many houses which are less than 10 years old have PVC pipes (although many have copper or galvanized pipes) and where they do, they have very low levels of lead.

New house with PVC plumbing ( <10 years)	Lead content/ppb	Old house with lead plumbing (>50 years)	Lead content/ppb
New House 1	7ppb	Old house 1	25ppb
New House 2	12ppb	Old house 2	32ppb
New House 3	9ppb	Old house 3	30ppb
New House 4	10ppb	Old house 4	32ppb
New House 5	9ppb	Old house 5	28ppb

Conclusion

The hypothesis that the older houses which use lead plumbing have a higher level of lead content in their tap water as compared to newer houses that use PVC pipes, is proven to be true.

The level of lead in our drinking water is now regulated in almost all countries. Water utility companies have to abide by strict regulations to control the level of contaminants such as lead, in our drinking water. Water is distributed to our homes through a network of pipes and most of the pipes in this network are regularly replaced over time. However the internal plumbing in older houses are not replaced and this may be a source of serious health risks to the occupants.
Lead poisoning causes many health problems and can especially affect children and unborn babies. Lead is not only found in water, but also in paint, contaminated soil, crockery and even some toys. Therefore, be wary of the products you buy and ensure that they are lead-free. 

Also consider

The experiment can also be performed using testing kits such as Prolab, to reduce the cost.
Try to modify this experiment to check the level of copper in tap water.

References

• Common types of piping - http://www.onlinetips.org/pipe-choose
• What you need to know about lead in the tap water -http://www.mwra.com/04water/html/qual6leadinfo.htm